# Search a list

Search a list
You are encouraged to solve this task according to the task description, using any language you may know.

Find the index of a string (needle) in an indexable, ordered collection of strings (haystack).

Raise an exception if the needle is missing.

If there is more than one occurrence then return the smallest index to the needle.

Extra credit

Return the largest index to a needle that has multiple occurrences in the haystack.

## 11l

Translation of: Python
V haystack = [‘Zig’, ‘Zag’, ‘Wally’, ‘Ronald’, ‘Bush’, ‘Krusty’, ‘Charlie’, ‘Bush’, ‘Bozo’]

L(needle) (‘Washington’, ‘Bush’)
X.try
print(haystack.index(needle)‘ ’needle)
X.catch ValueError
print(needle‘ is not in haystack’)
Output:
Washington is not in haystack
4 Bush


## ACL2

(defun index-of-r (e xs i)
(cond ((endp xs) nil)
((equal e (first xs)) i)
(t (index-of-r e (rest xs) (1+ i)))))

(defun index-of (e xs)
(index-of-r e xs 0))


## Acornsoft Lisp

Acornsoft Lisp does not have strings, so symbols would be used instead. That also allows us to use eq as the test.

(defun first-index (word words (i . 0))
(loop
(until (null words)
(error word '! is! missing))
(until (eq word (car words))
i)
(setq words (cdr words))

(defun last-index (word words (i . 0) (last-i . nil))
(loop
(until (null words)
(cond (last-i) (t (error word '! is! missing))))
(cond ((eq word (car words))
(setq last-i i)))
(setq words (cdr words))


## Action!

DEFINE PTR="CARD"

INT FUNC Search(PTR ARRAY texts INT count CHAR ARRAY text)
INT i

FOR i=0 TO count-1
DO
IF SCompare(texts(i),text)=0 THEN
RETURN (i)
FI
OD
RETURN (-1)

PROC Test(PTR ARRAY texts INT count CHAR ARRAY text)
INT index

index=Search(texts,count,text)
IF index=-1 THEN
PrintF("""%S"" is not in haystack.%E",text)
ELSE
PrintF("""%S"" is on index %I in haystack.%E",text,index)
FI
RETURN

PROC Main()
PTR ARRAY texts(7)

texts(0)="Monday"
texts(1)="Tuesday"
texts(2)="Wednesday"
texts(3)="Thursday"
texts(4)="Friday"
texts(5)="Saturday"
texts(6)="Sunday"

Test(texts,7,"Monday")
Test(texts,7,"Sunday")
Test(texts,7,"Thursday")
Test(texts,7,"Weekend")
RETURN
Output:
"Monday" is on index 0 in haystack.
"Sunday" is on index 6 in haystack.
"Thursday" is on index 3 in haystack.
"Weekend" is not in haystack.


## ActionScript

### Using the built-in Error class

var list:Vector.<String> = Vector.<String>(["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"]);
function lowIndex(listToSearch:Vector.<String>, searchString:String):int
{
var index:int = listToSearch.indexOf(searchString);
if(index == -1)
return index;
}

function highIndex(listToSearch:Vector.<String>, searchString:String):int
{
var index:int = listToSearch.lastIndexOf(searchString);
if(index == -1)
return index;
}


### Using a custom error

In StringNotFoundError.as:

package {
public class StringNotFoundError extends Error {
public function StringNotFoundError(message:String) {
super(message);
}
}
}


In a separate file:

import StringNotFoundError;
var list:Vector.<String> = Vector.<String>(["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"]);
function lowIndex(listToSearch:Vector.<String>, searchString:String):int
{
var index:int = listToSearch.indexOf(searchString);
if(index == -1)
return index;
}

function highIndex(listToSearch:Vector.<String>, searchString:String):int
{
var index:int = listToSearch.lastIndexOf(searchString);
if(index == -1)
return index;
}


with Ada.Strings.Unbounded;  use Ada.Strings.Unbounded;

procedure Test_List_Index is
Not_In : exception;

type List is array (Positive range <>) of Unbounded_String;

function Index (Haystack : List; Needle : String) return Positive is
begin
for Index in Haystack'Range loop
if Haystack (Index) = Needle then
return Index;
end if;
end loop;
raise Not_In;
end Index;

-- Functions to create lists
function "+" (X, Y : String) return List is
begin
return (1 => To_Unbounded_String (X), 2 => To_Unbounded_String (Y));
end "+";

function "+" (X : List; Y : String) return List is
begin
return X & (1 => To_Unbounded_String (Y));
end "+";

Haystack : List := "Zig"+"Zag"+"Wally"+"Ronald"+"Bush"+"Krusty"+"Charlie"+"Bush"+"Bozo";

procedure Check (Needle : String) is
begin
Put (Needle);
Put_Line ("at" & Positive'Image (Index (Haystack, Needle)));
exception
when Not_In => Put_Line (" is not in");
end Check;
begin
Check ("Washington");
Check ("Bush");
end Test_List_Index;

Output:
Washington is not in
Bushat 5


## Aime

void
search(list l, text s)
{
integer i;

i = 0;
while (i < ~l) {
if (l[i] == s) {
break;
}
i += 1;
}

o_(s, " is ", i == ~l ? "not in the haystack" : "at " + itoa(i), "\n");
}

integer
main(void)
{
list l;

l = l_effect("Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty",
"Charlie", "Bush", "Boz", "Zag");
__ucall(search, 1, 1, l, "Bush", "Washington", "Zag");

return 0;
}
Output:
Bush is at 4
Washington is not in the haystack
Zag is at 1

## ALGOL 68

### Using a FORMAT "value error" exception

Works with: ALGOL 68 version Revision 1 - no extensions to language used
Works with: ALGOL 68G version Any - tested with release 1.18.0-9h.tiny
 FORMAT hay stack := $c("Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo")$;

FILE needle exception; STRING ref needle;
associate(needle exception, ref needle);

PROC index = (FORMAT haystack, REF STRING needle)INT:(
INT out;
ref needle := needle;
getf(needle exception,(haystack, out));
out
);

test:(
[]STRING needles = ("Washington","Bush");
FOR i TO UPB needles DO
STRING needle := needles[i];
on value error(needle exception, (REF FILE f)BOOL: value error);
printf(($d" "gl$,index(hay stack, needle), needle));
end on value error;
value error:
printf(($g" "gl$,needle, "is not in haystack"));
end on value error: reset(needle exception)
OD
)
Output:
Washington is not in haystack
5 Bush


### Using a manual FOR loop with no exception

Works with: ALGOL 68 version Revision 1 - no extensions to language used
Works with: ALGOL 68G version Any - tested with release 1.18.0-9h.tiny
 []STRING hay stack = ("Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo");

PROC index = ([]STRING hay stack, STRING needle)INT:(
INT index;
FOR i FROM LWB hay stack TO UPB hay stack DO
index := i;
IF hay stack[index] = needle THEN
found
FI
OD;
else:
LWB hay stack - 1
EXIT
found:
index
);
test:(
[]STRING needles = ("Washington","Bush");
FOR i TO UPB needles DO
STRING needle := needles[i];
INT result = index(hay stack, needle);
IF result >= LWB hay stack THEN
printf(($d" "gl$, result, needle))
ELSE
printf(($g" "gl$,needle, "is not in haystack"))
FI
OD
)
Output:
Washington is not in haystack
5 Bush


## Arturo

haystack: [Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo]

loop [Bush Washington] 'needle [
i: index haystack needle

if? empty? i    -> panic ~"|needle| is not in haystack"
else            -> print [i needle]
]

Output:
4 Bush
>> Error | Washington is not in haystack

## AutoHotkey

haystack = Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo
needle = bush, washington
Loop, Parse, needle, ,
{
If InStr(haystack, A_LoopField)
MsgBox, % A_LoopField
Else
MsgBox % A_LoopField . " not in haystack"
}


## AWK

If we use an awk array indexed with "the order" of the string, to check if the needle is in the haystack we must walk the whole array; if we use the string itself as index (in awk index for an array is indeed an hash), and put its "index" (order number in the list) as associated value, we can fastly check if the needle is in the haystack. But we can't fastly use its order number to get the string value at that position.

In the following implementation we can reach the strings by numeric index with the array haystack_byorder (so, e.g. haystack_byorder[4] gives Bush), and know the "position" of the needle (if it exists) using it as string index for the array haystack, as example does. (Beware: this method does not work when there are duplicates!)

#! /usr/bin/awk -f
BEGIN {
# create the array, using the word as index...
words="Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo";
split(words, haystack_byorder, " ");
j=0;
for(idx in haystack_byorder) {
haystack[haystack_byorder[idx]] = j;
j++;
}
# now check for needle (we know it is there, so no "else")...
if ( "Bush" in haystack ) {
print "Bush is at " haystack["Bush"];
}
# check for unexisting needle
if ( "Washington" in haystack ) {
print "impossible";
} else {
print "Washington is not here";
}
}


## BASIC

Works with: QBasic
DATA foo, bar, baz, quux, quuux, quuuux, bazola, ztesch, foo, bar, thud, grunt
DATA foo, bar, bletch, foo, bar, fum, fred, jim, sheila, barney, flarp, zxc
DATA spqr, wombat, shme, foo, bar, baz, bongo, spam, eggs, snork, foo, bar
DATA zot, blarg, wibble, toto, titi, tata, tutu, pippo, pluto, paperino, aap
DATA noot, mies, oogle, foogle, boogle, zork, gork, bork

DIM haystack(54) AS STRING
DIM needle AS STRING, found AS INTEGER, L0 AS INTEGER

FOR L0 = 0 TO 54
NEXT

DO
INPUT "Word to search for? (Leave blank to exit) ", needle
IF needle <> "" THEN
FOR L0 = 0 TO UBOUND(haystack)
IF UCASE$(haystack(L0)) = UCASE$(needle) THEN
found = 1
PRINT "Found "; CHR$(34); needle; CHR$(34); " at index "; LTRIM$(STR$(L0))
END IF
NEXT
IF found < 1 THEN
PRINT CHR$(34); needle; CHR$(34); " not found"
END IF
ELSE
EXIT DO
END IF
LOOP

Output:
 Word to search for? (Leave blank to exit) foo
Found "foo" at index 0
Found "foo" at index 8
Found "foo" at index 12
Found "foo" at index 15
Found "foo" at index 27
Found "foo" at index 34
Word to search for? (Leave blank to exit) bar
Found "bar" at index 1
Found "bar" at index 9
Found "bar" at index 13
Found "bar" at index 16
Found "bar" at index 28
Found "bar" at index 35
Word to search for? (Leave blank to exit) baz
Found "baz" at index 2
Found "baz" at index 29
Word to search for? (Leave blank to exit)


### BASIC256

Translation of: Yabasic
list$= "mouse,hat,cup,deodorant,television,soap,methamphetamine,severed cat heads,cup" n$ = explode(list$, ",") t = 0 : j = 0 input string "Enter string to search: ", linea$

for i = 0 to n$[?]-1 if linea$ = n$[i] then if not t then print "First index for "; linea$; ": "; i
t = i
j += 1
end if
next

if t = 0 then
else
if j > 1 then print "Last index for "; linea$; ": "; t end if ### BBC BASIC  DIM haystack$(27)
haystack$() = "alpha","bravo","charlie","delta","echo","foxtrot","golf", \ \ "hotel","india","juliet","kilo","lima","mike","needle", \ \ "november","oscar","papa","quebec","romeo","sierra","tango", \ \ "needle","uniform","victor","whisky","x-ray","yankee","zulu" needle$ = "needle"
maxindex% = DIM(haystack$(), 1) FOR index% = 0 TO maxindex% IF needle$ = haystack$(index%) EXIT FOR NEXT IF index% <= maxindex% THEN PRINT "First found at index "; index% FOR last% = maxindex% TO 0 STEP -1 IF needle$ = haystack$(last%) EXIT FOR NEXT IF last%<>index% PRINT "Last found at index "; last% ELSE ERROR 100, "Not found" ENDIF  ### IS-BASIC 100 PROGRAM "Search.bas" 110 STRING A$(1 TO 55)*8
120 FOR I=1 TO 55
130   READ A$(I) 140 PRINT A$(I);" ";
150 NEXT
160 DO
170   PRINT :INPUT PROMPT "Word to seatch for? (Leave blank to exit) ":S$180 LET S$=LCASE$(LTRIM$(RTRIM$(S$))):LET FOUND=0
190   IF S$="" THEN EXIT DO 200 FOR I=LBOUND(A$) TO UBOUND(A$) 210 IF A$(I)=S$THEN LET FOUND=-1:PRINT "Found """;S$;""" at index";I
220   NEXT
230   IF NOT FOUND THEN PRINT """";S$;""" not found." 240 LOOP 250 DATA foo,bar,baz,quux,quuux,quuuux,bazola,ztesch,foo,bar,thud,grunt,foo,bar,bletch,foo,bar,fum,fred,jim,sheila,barney,flarp,zxc 260 DATA spqr,wombat,shme,foo,bar,baz,bongo,spam,eggs,snork,foo,bar,zot,blarg,wibble,toto,titi,tata,tutu,pippo,pluto,paperino,aap,noot,mies,oogle,foogle,boogle,zork,gork,bork ### FreeBASIC FreeBASIC doesn't have exceptions so we use a different approach to check if the needle is present or not in the haystack: ' FB 1.05.0 Win64 ' Works FB 1.05.0 Linux Mint 64 Function tryFindString(s() As String, search As String, ByRef index As Integer) As Boolean Dim length As Integer = UBound(s) - LBound(s) + 1 If length = 0 Then index = LBound(s) - 1 '' outside array Return False End If For i As Integer = LBound(s) To UBound(s) If s(i) = search Then index = i '' first occurrence Return True End If Next index = LBound(s) - 1 '' outside array Return False End Function Function tryFindLastString(s() As String, search As String, ByRef index As Integer) As Boolean Dim length As Integer = UBound(s) - LBound(s) + 1 If length = 0 Then index = LBound(s) - 1 '' outside array Return False End If Dim maxIndex As Integer = LBound(s) - 1 '' outside array For i As Integer = LBound(s) To UBound(s) If s(i) = search Then maxIndex = i End If Next If maxIndex > LBound(s) - 1 Then index = maxIndex '' last occurrence Return True Else Return False End If End Function Dim haystack(1 To 9) As String = {"Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo"} Dim needle(1 To 4) As String = {"Zag", "Krusty", "Washington", "Bush"} Dim As Integer index Dim As Boolean found For i As Integer = 1 To 4 found = tryFindString(haystack(), needle(i), index) If found Then Print needle(i); " found first at index"; index Else Print needle(i); " is not present" End If Next found = tryFindLastString(haystack(), needle(4), index) If found Then Print needle(4); " found last at index"; index Else Print needle(4); " is not present" End If Print Print "Press any key to quit" Sleep Output: Zag found first at index 2 Krusty found first at index 6 Washington is not present Bush found first at index 5 Bush found last at index 8  ### Gambas Public Sub Main() Dim sHaystack As String[] = ["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"] Dim sNeedle As String = "Charlie" Dim sOutput As String = "No needle found!" Dim siCount As Short For siCount = 0 To sHaystack.Max If sNeedle = sHaystack[siCount] Then sOutPut = sNeedle & " found at index " & Str(siCount) Break End If Next Print sOutput End Output: Charlie found at index 6  ### Liberty BASIC haystack$="apple orange pear cherry melon peach banana needle blueberry mango strawberry needle "
haystack$=haystack$+"pineapple grape kiwi blackberry plum raspberry needle cranberry apricot"

idx=1
do until word$(haystack$,idx)=""
idx=idx+1
loop
total=idx-1

needle$="needle" 'index of first occurrence for i = 1 to total if word$(haystack$,i)=needle$ then exit for
next
print needle$;" first found at index ";i 'index of last occurrence for j = total to 1 if word$(haystack$,j)=needle$ then exit for
next
print needle$;" last found at index ";j if i<>j then print "Multiple instances of ";needle$
else
print "Only one instance of ";needle$;" in list." end if 'raise exception needle$="cauliflower"
for k=1 to total
if word$(haystack$,k)=needle$then exit for next if k>total then print needle$;" not found in list."
else
print needle$;" found at index ";k end if ### PowerBASIC FUNCTION PBMAIN () AS LONG DIM haystack(54) AS STRING ARRAY ASSIGN haystack() = "foo", "bar", "baz", "quux", "quuux", "quuuux", _ "bazola", "ztesch", "foo", "bar", "thud", "grunt", "foo", _ "bar", "bletch", "foo", "bar", "fum", "fred", "jim", _ "sheila", "barney", "flarp", "zxc", "spqr", ";wombat", "shme", _ "foo", "bar", "baz", "bongo", "spam", "eggs", "snork", "foo", _ "bar", "zot", "blarg", "wibble", "toto", "titi", "tata", _ "tutu", "pippo", "pluto", "paperino", "aap", "noot", "mies", _ "oogle", "foogle", "boogle", "zork", "gork", "bork" DIM needle AS STRING, found AS LONG, lastFound AS LONG DO needle = INPUTBOX$("Word to search for? (Leave blank to exit)")
IF needle <> "" THEN
' collate ucase -> case insensitive
ARRAY SCAN haystack(), COLLATE UCASE, = needle, TO found
IF found > 0 THEN
lastFound = found
MSGBOX "Found """ & needle & """ at index " & TRIM$(STR$(found - 1))
IF found < UBOUND(haystack) THEN
DO
ARRAY SCAN haystack(lastFound), COLLATE UCASE, = needle, TO found
IF found > 0 THEN
MSGBOX "Another occurence of """ & needle & """ at index " & _
TRIM$(STR$(found + lastFound - 1))
lastFound = found + lastFound
ELSE
MSGBOX "No more occurences of """ & needle & """ found"
EXIT DO 'will exit inner DO, not outer
END IF
LOOP
END IF
ELSE
MSGBOX "No occurences of """ & needle & """ found"
END IF
ELSE
EXIT DO
END IF
LOOP
END FUNCTION

### PureBasic

If OpenConsole()  ; Open a simple console to interact with user
NewList Straws.s()
Define Straw$, target$="TBA"
Define found

Restore haystack ; Read in all the straws of the haystack.
Repeat
Read.s Straw$If Straw$<>""
Straws()=UCase(Straw$) Continue Else Break EndIf ForEver While target$<>""
Print(#CRLF$+"Enter word to search for (leave blank to quit) :"): target$=Input()
ResetList(Straws()): found=#False
While NextElement(Straws())
If UCase(target$)=Straws() found=#True PrintN(target$+" found as index #"+Str(ListIndex(Straws())))
EndIf
Wend
EndIf
Wend
EndIf

DataSection
haystack:
Data.s "Zig","Zag","Zig","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo",""
EndDataSection

### Run BASIC

haystack$= ("Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo Bush ") needle$   = "Zag Wally Bush Chicken"

while word$(needle$,i+1," ") <> ""
i  = i + 1
thisNeedle$= word$(needle$,i," ") + " " j = instr(haystack$,thisNeedle$) k1 = 0 k = instr(haystack$,thisNeedle$,j+1) while k <> 0 k1 = k k = instr(haystack$,thisNeedle$,k+1) wend if j <> 0 then print thisNeedle$;" located at:";j;
if k1 <> 0 then print " Last position located at:";k1;
print
else
print thisNeedle$;" is not in the list" end if wend Output: Zag located at:5 Wally located at:9 Bush located at:22 Last position located at:52 Chicken is not in the list ### Yabasic list$ = "mouse,hat,cup,deodorant,television,soap,methamphetamine,severed cat heads,cup"

dim item$(1) n = token(list$, item$(), ",") line input "Enter string to search: " line$
for i = 1 to n
if line$= item$(i) then
if not t print "First index for ", line$, ": ", i t = i j = j + 1 end if next if t = 0 then print "String not found in list" else if j > 1 print "Last index for ", line$, ": ", t
end if

## Batch File

The index of this simple implementation is 1-based. The "haystack" data are borrowed from the BASIC implementation.

@echo off
setlocal enabledelayedexpansion

%==Sample list==%
set "data=foo, bar, baz, quux, quuux, quuuux, bazola, ztesch, foo, bar, thud, grunt"
set "data=%data% foo, bar, bletch, foo, bar, fum, fred, jim, sheila, barney, flarp, zxc"
set "data=%data% spqr, wombat, shme, foo, bar, baz, bongo, spam, eggs, snork, foo, bar"
set "data=%data% zot, blarg, wibble, toto, titi, tata, tutu, pippo, pluto, paperino, aap"
set "data=%data% noot, mies, oogle, foogle, boogle, zork, gork, bork"

%==Sample "needles" [whitespace is the delimiter]==%
set "needles=foo bar baz jim bong"

%==Counting and Seperating each Data==%
set datalen=0
for %%. in (!data!) do (
set /a datalen+=1
set data!datalen!=%%.
)
%==Do the search==%
for %%A in (!needles!) do (
set "first="
set "last="
set "found=0"
for /l %%B in (1,1,%datalen%) do (
if "!data%%B!" == "%%A" (
set /a found+=1
if !found! equ 1 set first=%%B
set last=%%B
)
)

if !found! equ 1 echo."%%A": Found once in index [!first!].
if !found! gtr 1 echo."%%A": Found !found! times. First instance:[!first!] Last instance:[!last!].

)
%==We are done==%
echo.
pause
Output:
"foo": Found 6 times. First instance:[1] Last instance:[35].
"bar": Found 6 times. First instance:[2] Last instance:[36].
"baz": Found 2 times. First instance:[3] Last instance:[30].
"jim": Found once in index [20].

Press any key to continue . . .

## BQN

Generally, ⊐ (Index Of) is used to find the indices of the right argument array's elements in the left argument. It returns the length of the left argument 𝕨 if the argument is not present.

The given IndexOf function is written to satisfy question requirements (throwing exceptions), and it is not recommended for use in production.

list ← ⟨"Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"⟩

IndexOf ← {
("Error: '" ∾𝕩∾ "' Not found in list") ! (≠𝕨)≠ind ← ⊑𝕨⊐⋈𝕩
ind
}

•Show list ⊐ "Wally"‿"Hi" # intended
•Show list IndexOf "Wally"
list IndexOf "Hi"

⟨ 2 10 ⟩
2

("Error: '" ∾𝕩∾ "' Not found in list") ! (≠𝕨)≠ind ← ⊑𝕨⊐⋈𝕩
^

list IndexOf "Hi"
^^^^^^^


## Bracmat

For both subtasks, pattern matching is used. The second subtasks proceeds in two steps. First, the first word that occurs twice is found (if it exists). Then, the last occurrence of this word is found using forced backtracking (see the ~ node) until failure.

(     return the largest index to a needle that has multiple
occurrences in the haystack and print the needle
: ?list
& (   !list:? haystack [?index ?
& out$("The word 'haystack' occurs at 1-based index" !index) | out$"The word 'haystack' does not occur"
)
& (   !list
: ? %@?needle ? !needle ?
: ( ? !needle [?index (?&~)
|   ?
&   out
$( str$ ( "The word '"
!needle
"' occurs more than once. The last 1-based index is "
!index
)
)
)
| out$"No word occurs more than once." ) ); Output: The word 'haystack' occurs at 1-based index 14 The word 'the' occurs more than once. The last 1-based index is 17 ## Burlesque blsq ) {"Zig" "Zag" "Wally" "Bush" "Ronald" "Bush"}"Bush"Fi 3 If you want all indices: blsq ) {"Zig" "Zag" "Wally" "Bush" "Ronald" "Bush"}{"Bush"==}fI {3 5} ## C #include <stdio.h> #include <string.h> const char *haystack[] = { "Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag", NULL }; int search_needle(const char *needle, const char **hs) { int i = 0; while( hs[i] != NULL ) { if ( strcmp(hs[i], needle) == 0 ) return i; i++; } return -1; } int search_last_needle(const char *needle, const char **hs) { int i, last=0; i = last = search_needle(needle, hs); if ( last < 0 ) return -1; while( hs[++i] != NULL ) { if ( strcmp(needle, hs[i]) == 0 ) { last = i; } } return last; } int main() { printf("Bush is at %d\n", search_needle("Bush", haystack)); if ( search_needle("Washington", haystack) == -1 ) printf("Washington is not in the haystack\n"); printf("First index for Zag: %d\n", search_needle("Zag", haystack)); printf("Last index for Zag: %d\n", search_last_needle("Zag", haystack)); return 0; }  Output: Bush is at 4 Washington is not in the haystack First index for Zag: 1 Last index for Zag: 9 ## C# using System; using System.Collections.Generic; class Program { static void Main(string[] args) { List<string> haystack = new List<string>() { "Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo" }; foreach (string needle in new string[] { "Washington", "Bush" }) { int index = haystack.IndexOf(needle); if (index < 0) Console.WriteLine("{0} is not in haystack",needle); else Console.WriteLine("{0} {1}",index,needle); } } }  ## C++ Works with: g++ version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21) The following code shows three different ways to solve the task. #include <string> #include <algorithm> #include <iterator> #include <cstddef> #include <exception> #include <iostream> // an exception to throw (actually, throwing an exception in this case is generally considered bad style, but it's part of the task) class not_found: public std::exception { public: not_found(std::string const& s): text(s + " not found") {} char const* what() const throw() { return text.c_str(); } ~not_found() throw() {} private: std::string text; }; // needle search function, C-style interface version using standard library std::size_t get_index(std::string* haystack, int haystack_size, std::string needle) { std::size_t index = std::find(haystack, haystack+haystack_size, needle) - haystack; if (index == haystack_size) throw not_found(needle); else return index; } // needle search function, completely generic style, needs forward iterators // (works with any container, but inefficient if not random-access-iterator) template<typename FwdIter> typename std::iterator_traits<FwdIter>::difference_type fwd_get_index(FwdIter first, FwdIter last, std::string needle) { FwdIter elem = std::find(first, last, needle); if (elem == last) throw not_found(needle); else return std::distance(first, elem); } // needle search function, implemented directly, needs only input iterator, works efficiently with all sequences template<typename InIter> typename std::iterator_traits<InIter>::difference_type generic_get_index(InIter first, InIter last, std::string needle) { typename std::iterator_traits<InIter>::difference_type index = 0; while (first != last && *first != needle) { ++index; ++first; } if (first == last) throw not_found(needle); else return index; } // ---------------------------------------------------------------------------------------------------------------------------------- // a sample haystack (content copied from Haskell example) std::string haystack[] = { "Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo" }; // some useful helper functions template<typename T, std::size_t sz> T* begin(T (&array)[sz]) { return array; } template<typename T, std::size_t sz> T* end(T (&array)[sz]) { return array + sz; } template<typename T, std::size_t sz> std::size_t size(T (&array)[sz]) { return sz; } // test function searching a given needle with each of the methods void test(std::string const& needle) { std::cout << "-- C style interface --\n"; try { std::size_t index = get_index(haystack, size(haystack), needle); std::cout << needle << " found at index " << index << "\n"; } catch(std::exception& exc) // better catch standard exceptions as well; me might e.g. run out of memory { std::cout << exc.what() << "\n"; } std::cout << "-- generic interface, first version --\n"; try { std::size_t index = fwd_get_index(begin(haystack), end(haystack), needle); std::cout << needle << " found at index " << index << "\n"; } catch(std::exception& exc) // better catch standard exceptions as well; me might e.g. run out of memory { std::cout << exc.what() << "\n"; } std::cout << "-- generic interface, second version --\n"; try { std::size_t index = generic_get_index(begin(haystack), end(haystack), needle); std::cout << needle << " found at index " << index << "\n"; } catch(std::exception& exc) // better catch standard exceptions as well; me might e.g. run out of memory { std::cout << exc.what() << "\n"; } } int main() { std::cout << "\n=== Word which only occurs once ===\n"; test("Wally"); std::cout << "\n=== Word occuring multiple times ===\n"; test("Bush"); std::cout << "\n=== Word not occuring at all ===\n"; test("Goofy"); }  Output: (note that in C++, indices start at 0)  === Word which only occurs once === -- C style interface -- Wally found at index 2 -- generic interface, first version -- Wally found at index 2 -- generic interface, second version -- Wally found at index 2 === Word occuring multiple times === -- C style interface -- Bush found at index 4 -- generic interface, first version -- Bush found at index 4 -- generic interface, second version -- Bush found at index 4 === Word not occuring at all === -- C style interface -- Goofy not found -- generic interface, first version -- Goofy not found -- generic interface, second version -- Goofy not found  ### C++11 /* new c++-11 features * list class * initialization strings * auto typing * lambda functions * noexcept * find * for/in loop */ #include <iostream> // std::cout #include <algorithm> // std::find #include <list> // std::list #include <vector> // std::vector #include <string> // string::basic_string using namespace std; // saves typing of "std::" before everything int main() { // initialization lists // create objects and fully initialize them with given values list<string> l { "Zig", "Zag", "Wally", "Homer", "Madge", "Watson", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bush", "Boz", "Zag" }; list<string> n { "Bush" , "Obama", "Homer", "Sherlock" }; // lambda function with auto typing // auto is easier to write than looking up the complicated // specialized iterator type that is actually returned. // Just know that it returns an iterator for the list at the position found, // or throws an exception if s in not in the list. // runtime_error is used because it can be initialized with a message string. auto contains = [](list<string> l, string s) throw(runtime_error) { auto r = find(begin(l), end(l), s ); if( r == end(l) ) throw runtime_error( s + " not found" ); return r; }; // returns an int vector with the indexes of the search string // The & is a "default capture" meaning that it "allows in" // the variables that are in scope where it is called by their // name to simplify things. auto index = [&](list<string> l, string s) noexcept { vector<int> index_v; int idx = 0; for(const string& r : l) { if( s.compare(r) == 0 ) // match -- add to vector index_v.push_back(idx); idx++; } // even though index_v is local to the lambda function, // c++11 move semantics does what you want and returns it // live and intact instead of destroying it or returning a copy. // (very efficient for large objects!) return index_v; }; // range-based for loop // s is a read-only reference, not a copy for (const string& s : n) // new iteration syntax is simple and intuitive { try { auto cont = contains( l , s); // checks if there is any match if( cont != l.end() ) // found at least one { vector<int> vf = index( l, s ); cout << "l contains: " << s << " at " ; for(auto x : vf) // auto will resolve to int { cout << x << " "; } // if vector is empty this doesn't run cout << "\n"; } } catch (const runtime_error& r) // string not found { cout << r.what() << "\n"; continue; // try next string } } //for return 0; } // main /* end */  Output: l contains: Bush at 7 10 11 Obama not found l contains: Homer at 3 Sherlock not found  ## Ceylon shared test void searchAListTask() { value haystack = [ "Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo"]; assert(exists firstIdx = haystack.firstOccurrence("Bush")); assert(exists lastIdx = haystack.lastOccurrence("Bush")); assertEquals(firstIdx, 4); assertEquals(lastIdx, 7); }  ## Clojure (let [haystack ["Zig" "Zag" "Wally" "Ronald" "Bush" "Krusty" "Charlie" "Bush" "Bozo"]] (let [idx (.indexOf haystack "Zig")] (if (neg? idx) (throw (Error. "item not found.")) idx)))  Extra credit: Since Clojure vectors implement java.util.List, you can switch .indexOf for .lastIndexOf to find the highest index of your value. ## CLU % Search an indexable, ordered collection. % The collection needs to provide indexes' and fetch'; % the element type needs to provide equal'. search = proc [T, U: type] (haystack: T, needle: U) returns (int) signals (not_found) where T has indexes: itertype (T) yields (int), fetch: proctype (T,int) returns (U) signals (bounds), U has equal: proctype (U,U) returns (bool) for i: int in T$indexes(haystack) do
if needle = haystack[i] then return (i) end
end
signal not_found
end search

start_up = proc ()
as = array[string]
str_search = search[as,string]

po: stream := stream$primary_output() haystack: as := as$
["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"]
needles: as := as$["Ronald","McDonald","Bush","Obama"] for needle: string in as$elements(needles) do
stream$puts(po, needle || ": ") stream$putl(po, int$unparse(str_search(haystack,needle))) except when not_found: stream$putl(po, "not found")
end
end
end start_up
Output:
Ronald: 4
Bush: 5
Obama: not found

## COBOL

*> This is written to COBOL85, which does not include exceptions.
IDENTIFICATION DIVISION.
PROGRAM-ID. Search-List.

DATA DIVISION.
WORKING-STORAGE SECTION.
01  haystack-area.
78  Haystack-Size VALUE 10.
03  haystack-data.
05  FILLER     PIC X(7) VALUE "Zig".
05  FILLER     PIC X(7) VALUE "Zag".
05  FILLER     PIC X(7) VALUE "Wally".
05  FILLER     PIC X(7) VALUE "Ronald".
05  FILLER     PIC X(7) VALUE "Bush".
05  FILLER     PIC X(7) VALUE "Krusty".
05  FILLER     PIC X(7) VALUE "Charlie".
05  FILLER     PIC X(7) VALUE "Bush".
05  FILLER     PIC X(7) VALUE "Boz".
05  FILLER     PIC X(7) VALUE "Zag".

03  haystack-table REDEFINES haystack-data.
05  haystack   PIC X(7) OCCURS Haystack-Size TIMES
INDEXED BY haystack-index.

01  needle             PIC X(7).

PROCEDURE DIVISION.
main.
MOVE "Bush" TO needle
PERFORM find-needle

MOVE "Goofy" TO needle
PERFORM find-needle

MOVE "Bush" TO needle
PERFORM find-last-of-needle

GOBACK
.

find-needle.
SEARCH haystack
AT END

WHEN haystack (haystack-index) = needle
DISPLAY "Found " needle " at " haystack-index "."
END-SEARCH
.

find-last-of-needle.
PERFORM VARYING haystack-index FROM Haystack-Size BY -1
UNTIL haystack-index = 0
OR haystack (haystack-index) = needle
END-PERFORM

IF haystack-index = 0
ELSE
DISPLAY "Found last of " needle " at " haystack-index "."
END-IF
.

Output:
Found Bush    at +000000005.
Found last of Bush    at +000000008.


## Common Lisp

(let ((haystack '(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo)))
(dolist (needle '(Washington Bush))
(let ((index (position needle haystack)))
(if index
(progn (print index) (princ needle))
(progn (print needle) (princ "is not in haystack"))))))

Output:
WASHINGTON is not in haystack
4 BUSH


The position function solves this task elegantly.

CL-USER> (defparameter *list* '(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo))
*LIST*
CL-USER> (position 'Bush *list*)
4
CL-USER> (position 'Bush *list* :from-end t)
7
CL-USER> (position 'Washington *list*)
NIL


## D

import std.algorithm, std.range, std.string;

auto firstIndex(R, T)(R hay, T needle) {
auto i = countUntil(hay, needle);
if (i == -1)
throw new Exception("No needle found in haystack");
return i;
}

auto lastIndex(R, T)(R hay, T needle) {
return walkLength(hay) - firstIndex(retro(hay), needle) - 1;
}

void main() {
auto h = split("Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo");
assert(firstIndex(h, "Bush") == 4);
assert(lastIndex(h, "Bush") == 7);
}


## Delphi

program Needle;

{$APPTYPE CONSOLE} uses SysUtils, Classes; var list: TStringList; needle: string; ind: Integer; begin list := TStringList.Create; try list.Append('triangle'); list.Append('fork'); list.Append('limit'); list.Append('baby'); list.Append('needle'); list.Sort; needle := 'needle'; ind := list.IndexOf(needle); if ind < 0 then raise Exception.Create('Needle not found') else begin Writeln(ind); Writeln(list[ind]); end; Readln; finally list.Free; end; end.  Output: 3 needle  ## DWScript var haystack : array of String = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"]; function Find(what : String) : Integer; begin Result := haystack.IndexOf(what); if Result < 0 then raise Exception.Create('not found'); end; PrintLn(Find("Ronald")); // 3 PrintLn(Find('McDonald')); // exception  ## E def haystack := ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"] /** meet the 'raise an exception' requirement */ def find(needle) { switch (haystack.indexOf1(needle)) { match ==(-1) { throw("an exception") } match index { return index } } } println(find("Ronald")) # prints 3 println(find("McDonald")) # will throw ## EasyLang haystack$[] = [ "Zig" "Zag" "Wally" "Ronald" "Bush" "Krusty" "Charlie" "Bush" "Boz" "Zag" ]
#
func getind needle$. for i to len haystack$[]
if haystack$[i] = needle$
return i
.
.
return 0
.
# arrays are 1 based
for n$in [ "Bush" "Washington" ] h = getind n$
if h = 0
print n$& " not found" else print n$ & " found at " & h
.
.

## Elena

ELENA 6.x :

import system'routines;
import extensions;

public program()
{
var haystack := new string[]{"Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo"};

new string[]{"Washington", "Bush"}.forEach::(needle)
{
var index := haystack.indexOfElement(needle);

if (index == -1)
{
console.printLine(needle," is not in haystack")
}
else
{
console.printLine(needle, " - ", index)
}
}
}

## Elixir

haystack = ~w(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo)

Enum.each(~w(Bush Washington), fn needle ->
index = Enum.find_index(haystack, fn x -> x==needle end)
if index, do: (IO.puts "#{index} #{needle}"),
else: raise "#{needle} is not in haystack\n"
end)

Output:
4 Bush
** (RuntimeError) Washington is not in haystack

search.exs:5: anonymous fn/1 in :elixir_compiler_0.__FILE__/1
(elixir) lib/enum.ex:537: Enum."-each/2-lists^foreach/1-0-"/2
(elixir) lib/enum.ex:537: Enum.each/2
(elixir) lib/code.ex:316: Code.require_file/2


## Erlang

Erlang lists can be accessed with the function lists:nth/2, which starts at 1 (first element). As such Erlang can be considered 1-indexed for this problem. Note that you could set the indexing to 0 by modifying the function call in pos/2.

-module(index).
-export([main/0]).

main() ->
Haystack = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"],
Needles = ["Washington","Bush"],
lists:foreach(fun ?MODULE:print/1, [{N,pos(N, Haystack)} || N <- Needles]).

pos(Needle, Haystack) -> pos(Needle, Haystack, 1).
pos(_, [], _) -> undefined;
pos(Needle, [Needle|_], Pos) -> Pos;
pos(Needle, [_|Haystack], Pos) -> pos(Needle, Haystack, Pos+1).

print({Needle, undefined}) -> io:format("~s is not in haystack.~n",[Needle]);
print({Needle, Pos}) -> io:format("~s at position ~p.~n",[Needle,Pos]).

Output:
Washington is not in haystack.
Bush at position 5.


## Euphoria

Works with: Euphoria version 4.0.3, 4.0.0 RC1 and later

The find_all function from the standard library's search.e does nearly all the needed work here.There may be other ways to do this using Euphoria's various sequence searching functions as part of the standard library (std/search.e) and/or built into the language. The procedure can be made into a function to search with other strings, take user input and give output of the searched haystack.

include std/search.e
include std/console.e

--the string "needle" and example haystacks to test the procedure
sequence searchStr1 = "needle"
sequence haystack1 = { "needle", "needle", "noodle", "node", "need", "needle  ", "needle" }
sequence haystack2 = {"spoon", "fork", "hay", "knife", "needle", "barn", "etcetera", "more hay", "needle", "a cow", "farmer", "needle", "dirt"}
sequence haystack3 = {"needle"}
sequence haystack4 = {"no", "need le s", "in", "this", "haystack"}
sequence haystack5 = {"knee", "needle", "dull", "needle"}
sequence haystack6 = {}

--search procedure with console output
procedure haystackSearch(sequence hStack)
sequence foundNeedles = find_all(searchStr1, hStack)
puts(1,"---------------------------------\r\n")
if object(foundNeedles) and length(foundNeedles) > 0 then
printf(1, "First needle found at index %d \r\n", foundNeedles[1])

if length(foundNeedles) > 1 then
printf(1, "Last needle found at index %d \r\n", foundNeedles[length(foundNeedles)] )

for i = 1 to length(foundNeedles) do
printf(1, "Needle #%d ", i)
printf(1, "was at index %d .\r\n", foundNeedles[i])
end for

else
puts(1, "There was only one needle found in this haystack. \r\n")
end if

else
puts(1, "Simulated exception - No needles found in this haystack.\r\n")
end if

end procedure

--runs the procedure on all haystacks
haystackSearch(haystack1)
haystackSearch(haystack2)
haystackSearch(haystack3)
haystackSearch(haystack4)
haystackSearch(haystack5)
haystackSearch(haystack6)
--wait for user to press a key to exit
any_key()
Output:
---------------------------------
First needle found at index 1
Last needle found at index 7
Needle #1 was at index 1 .
Needle #2 was at index 2 .
Needle #3 was at index 7 .
---------------------------------
First needle found at index 5
Last needle found at index 12
Needle #1 was at index 5 .
Needle #2 was at index 9 .
Needle #3 was at index 12 .
---------------------------------
First needle found at index 1
There was only one needle found in this haystack.
---------------------------------
Simulated exception - No needles found in this haystack.
---------------------------------
First needle found at index 2
Last needle found at index 4
Needle #1 was at index 2 .
Needle #2 was at index 4 .
---------------------------------
Simulated exception - No needles found in this haystack.
Press Any Key to continue...


## F#

List.findIndex (fun x -> x = "bar") ["foo"; "bar"; "baz"; "bar"]  // -> 1
// A System.Collections.Generic.KeyNotFoundException
// is raised, if the predicate does not evaluate to
// true for any list element.


## Factor

: find-index ( seq elt -- i )
'[ _ = ] find drop [ "Not found" throw ] unless* ; inline

: find-last-index ( seq elt -- i )
'[ _ = ] find-last drop [ "Not found" throw ] unless* ; inline

( scratchpad ) { "a" "b" "c" "d" "c" } "c" find-index .
2
( scratchpad ) { "a" "b" "c" "d" "c" } "c" find-last-index .
4


## Forth

Works with: 4tH version 3.61.5
include lib/row.4th

create haystack
," Zig"  ," Zag" ," Wally" ," Ronald" ," Bush" ," Krusty" ," Charlie"
," Bush" ," Boz" ," Zag" NULL ,
does>
dup >r 1 string-key row 2>r type 2r> ."  is "
if r> - ." at " . else r> drop drop ." not found" then cr
;

s" Washington" haystack s" Bush" haystack


Works with any ANS Forth

Needs the FMS-SI (single inheritance) library code located here: http://soton.mpeforth.com/flag/fms/index.html

include FMS-SI.f
include FMS-SILib.f

${ Dishonest Fake Left Karl Hillary Monica Bubba Hillary Multi-Millionaire } constant haystack : needleIndex { addr len$list | cnt -- idx }
0 to cnt  $list uneach: begin$list each:
while
@: addr len compare 0= if cnt exit then
cnt 1+ to cnt

: LastIndexOf { addr len $list | cnt last-found -- idx } 0 to cnt 0 to last-found$list uneach:
begin
$list each: while @: addr len compare 0= if cnt to last-found then cnt 1+ to cnt repeat last-found if last-found else true abort" Not found" then ; s" Hillary" haystack needleIndex . \ => 4 s" Hillary" haystack LastIndexOf . \ => 7 s" Washington" haystack needleIndex . \ => aborted: Not found  ## Fortran program main implicit none character(len=7),dimension(10) :: haystack = [ & 'Zig ',& 'Zag ',& 'Wally ',& 'Ronald ',& 'Bush ',& 'Krusty ',& 'Charlie',& 'Bush ',& 'Boz ',& 'Zag '] call find_needle('Charlie') call find_needle('Bush') contains subroutine find_needle(needle) implicit none character(len=*),intent(in) :: needle integer :: i do i=1,size(haystack) if (needle==haystack(i)) then write(*,'(A,I4)') trim(needle)//' found at index:',i return end if end do write(*,'(A)') 'Error: '//trim(needle)//' not found.' end subroutine find_needle end program main  ## FutureBasic window 1, @"Search a list" void local fn MyEnumeratorCallback( array as CFArrayRef, obj as CFTypeRef, index as NSUInteger, stp as ^BOOL, userData as ptr ) if ( fn StringIsEqual( obj, userData ) ) print obj;@" found at index ";index *stp = YES// stop enumeration end if if ( index == 0 ) then print userData;@" not found" end fn void local fn DoIt CFArrayRef haystack = @[@"Mike",@"Bravo",@"Tango",@"Uniform",@"Golf", @"Tango",@"Sierra",@"November",@"Zulu",@"Delta",@"Hotel",@"Juliet"] CFStringRef needle = @"Sierra" NSInteger index = fn ArrayIndexOfObject( haystack, needle ) if ( index != NSNotFound ) print needle;@" found at index ";index else print needle;@" not found" end if ArrayEnumerateObjectsWithOptions( haystack, NSEnumerationReverse, @fn MyEnumeratorCallback, (ptr)@"Tango" ) end fn fn DoIt HandleEvents Output: Sierra found at index 6 Tango found at index 5  ## GAP # First position is built-in haystack := Eratosthenes(10000);; needle := 8999;; Position(haystack, needle); # 1117 LastPosition := function(L, x) local old, new; old := 0; new := 0; while new <> fail do new := Position(L, x, old); if new <> fail then old := new; fi; od; return old; end; a := Shuffle(List([1 .. 100], x -> x mod 10)); # [ 0, 2, 4, 5, 3, 1, 0, 4, 8, 8, 2, 7, 6, 3, 3, 6, 4, 4, 3, 0, 7, 1, 8, 7, 2, 4, 7, 9, 4, 9, 4, 5, 9, 9, 6, 7, 8, 2, 3, # 5, 1, 5, 4, 2, 0, 9, 6, 1, 1, 2, 2, 0, 5, 7, 6, 8, 8, 3, 1, 9, 5, 1, 9, 6, 8, 9, 2, 0, 6, 2, 1, 6, 1, 1, 2, 5, 3, 3, # 0, 3, 5, 7, 5, 4, 6, 8, 0, 9, 8, 3, 7, 8, 0, 4, 9, 7, 0, 6, 5, 7 ] Position(a, 0); # 1 LastPosition(a, 0); # 97  See also Eratosthenes and Shuffle functions in RosettaCode. ## Go Data used by both examples below. (You can give multiple files to go run, like$ go run data.go example.go)

package main

var haystack = []string{"Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty",
"Charlie", "Bush", "Bozo", "Zag", "mouse", "hat", "cup", "deodorant",
"television", "soap", "methamphetamine", "severed cat heads", "foo",
"bar", "baz", "quux", "quuux", "quuuux", "bazola", "ztesch", "foo",
"bar", "thud", "grunt", "foo", "bar", "bletch", "foo", "bar", "fum",
"fred", "jim", "sheila", "barney", "flarp", "zxc", "spqr", ";wombat",
"shme", "foo", "bar", "baz", "bongo", "spam", "eggs", "snork", "foo",
"bar", "zot", "blarg", "wibble", "toto", "titi", "tata", "tutu", "pippo",
"pluto", "paperino", "aap", "noot", "mies", "oogle", "foogle", "boogle",
"zork", "gork", "bork", "sodium", "phosphorous", "californium",
"copernicium", "gold", "thallium", "carbon", "silver", "gold", "copper",
"helium", "sulfur"}


### Linear search

package main

import "fmt"

func main() {
printSearchForward("soap")
printSearchForward("gold")
printSearchForward("fire")
printSearchReverseMult("soap")
printSearchReverseMult("gold")
printSearchReverseMult("fire")
}

// First task solution uses panic as an exception-like mechanism, as requested
// by the task.  Note however, this is not idiomatic in Go and in fact
func printSearchForward(s string) {
fmt.Printf("Forward search: %s: ", s)
defer func() {
if x := recover(); x != nil {
if err, ok := x.(string); ok && err == "no match" {
fmt.Println(err)
return
}
panic(x)
}
}()
fmt.Println("smallest index =", searchForwardPanic(s))
}

func searchForwardPanic(s string) int {
for i, h := range haystack {
if h == s {
return i
}
}
panic("no match")
return -1
}

// Extra task, a quirky search for multiple occurrences.  This is written
// without panic, and shows more acceptable Go programming practice.
func printSearchReverseMult(s string) {
fmt.Printf("Reverse search for multiples: %s: ", s)
if i := searchReverseMult(s); i > -1 {
fmt.Println("largest index =", i)
} else {
fmt.Println("no multiple occurrence")
}
}

func searchReverseMult(s string) int {
largest := -1
for i := len(haystack) - 1; i >= 0; i-- {
switch {
case haystack[i] != s:
case largest == -1:
largest = i
default:
return largest
}
}
return -1
}

Output:
Forward search: soap: smallest index = 15
Forward search: gold: smallest index = 77
Forward search: fire: no match
Reverse search for multiples: soap: no multiple occurrence
Reverse search for multiples: gold: largest index = 81
Reverse search for multiples: fire: no multiple occurrence


### Map lookup

More efficient, if you're doing lots of lookups, is to build a map. This example doesn't completely conform to the task but gives the idea that you could store indexes as map values.

package main

import "fmt"

func main() {
m := map[string][]int{}
for i, needle := range haystack {
m[needle] = append(m[needle], i)
}
for _, n := range []string{"soap", "gold", "fire"} {
fmt.Println(n, m[n])
}
}

Output:
soap [15]
gold [77 81]
fire []


## Groovy

def haystack = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"]
def needles = ["Washington","Bush","Wally"]
needles.each { needle ->
def index = haystack.indexOf(needle)
def lastindex = haystack.lastIndexOf(needle)
if (index < 0) {
assert lastindex < 0
println needle + " is not in haystack"
} else {
println "First index: " + index + " " + needle
println "Last index:  " + lastindex + " " + needle
}
}

Output:
Washington is not in haystack
First index: 4 Bush
Last index:  7 Bush
First index: 2 Wally
Last index:  2 Wally


Libraries and data:

import Data.List

haystack=["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"]
needles = ["Washington","Bush"]


I use 'lambda' notation for readability.

Find 'just' an index:
*Main> map (\x -> (x,elemIndex x haystack)) needles
[("Washington",Nothing),("Bush",Just 4)]


Want to know if there are there more Bushes hiding in the haystack?

*Main> map (\x -> (x,elemIndices x haystack)) needles
[("Washington",[]),("Bush",[4,7])]


To be complete. Here is the 'point free' version of the task:

*Main> ((,) <*> flip elemIndex haystack) <$> needles [("Washington",Nothing),("Bush",Just 4)]  ## HicEst CHARACTER haystack='Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo.' CHARACTER needle*10 DLG(TItle="Enter search string", Edit=needle) n = EDIT(Text=haystack, Option=2, End, Count=needle) ! Option = word IF( n == 0 ) THEN WRITE(Messagebox="!") needle, "not found" ! bus not found ELSE first = EDIT(Text=needle, LeXicon=haystack) WRITE(ClipBoard) "First ", needle, "found in position ", first ! First bush found in position 5 last = EDIT(Text=haystack, End, Left=needle, Count=" ") + 1 WRITE(ClipBoard) "Last ", needle, "found in position ", last ! Last bush found in position 8 ENDIF ## Icon and Unicon link lists procedure main() haystack := ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"] # the haystack every needle := !["Bush","Washington"] do { # the needles if i := lindex(haystack,needle) then { # first occurrence write("needle=",needle, " is at position ",i," in haystack.") if i <:= last(lindex,[haystack,needle]) then # last occurrence write("needle=",needle, " is at last position ",i," in haystack.") } else { write("needle=",needle, " is not in haystack.") runerr(500,needle) # throw an error } } end procedure last(p,arglist) #: return the last generation of p(arglist) or fail local i every i := p!arglist return \i end  Taken from the public domain Icon Programming Library's lindex in lists which generates list indices for x of any type procedure lindex(lst, x) #: generate indices for items matching x local i every i := 1 to *lst do if lst[i] === x then suspend i end  Output: needle=Bush is at position 5 in haystack. needle=Bush is at last position 8 in haystack. needle=Washington is not in haystack. Run-time error 500 File haystack.icn; Line 7 program malfunction offending value: "Washington" Traceback: main(list_1 = []) runerr(500,"Washington") from line 7 in haystack.icn ## Io List has a indexOf method which does not raise an exception on lookup failure but returns nil therefore I extend List with a firstIndex method that does raise an exception. I also create a lastIndex extension that finds the last index of a matching object by iterating in reverse over the list. Note that all these methods find any object not just strings. NotFound := Exception clone List firstIndex := method(obj, indexOf(obj) ifNil(NotFound raise) ) List lastIndex := method(obj, reverseForeach(i,v, if(v == obj, return i) ) NotFound raise ) haystack := list("Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo") list("Washington","Bush") foreach(needle, try( write("firstIndex(\"",needle,"\"): ") writeln(haystack firstIndex(needle)) )catch(NotFound, writeln(needle," is not in haystack") )pass try( write("lastIndex(\"",needle,"\"): ") writeln(haystack lastIndex(needle)) )catch(NotFound, writeln(needle," is not in haystack") )pass )  Output: firstIndex("Washington"): Washington is not in haystack lastIndex("Washington"): Washington is not in haystack firstIndex("Bush"): 4 lastIndex("Bush"): 7 ## J J has a general and optimized lookup function, i. For example:  Haystack =: ;:'Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo' Needles =: ;:'Washington Bush' Haystack i. Needles NB. first positions 9 4 Haystack i: Needles NB. last positions 9 7  Note that the arguments to i. can be anything (ie either or both may be scalars, lists, multidimensional arrays, etc). Nonmatches get a result of 1+largest valid index. Other search primitives include: e. finds whether items are members of a set, returning a bitmask to select the members:  Needles e. Haystack 0 1 1 2 3 4 5 6 7 8 9 e. 2 3 5 60 0 1 1 0 1 0 0 0 0  I. finds indices, but performs a binary search (which requires that the list being searched is sorted). This can be useful for finding non-exact matches (the index of the next value is returned for non-exact matches).  1 2 3 4 5 6 7 8 9 I. 2 3 5 60 6.66 1 2 4 9 6 (;:'eight five four nine one seven six three two') I. ;:'two three five sixty' 8 7 1 7  To format output similar to the other examples, one might write:  Haystack ;:^:_1@(] ,. [ ((<'is not in haystack')"_)(#@[ I.@:= ])(8!:0@])} i.) Needles Washington is not in haystack Bush 4  Or broken up into components and defined as a verb/function for finding the last positions:  msg=: (<'is not in haystack')"_ NB. not found message idxmissing=: #@[ I.@:= ] NB. indices of items not found fmtdata=: 8!:0@] NB. format atoms as boxed strings findLastIndex=: ;:inv@(] ,. [ msgidxmissingfmtdata} i:) Haystack findLastIndex Needles NB. usage Washington is not in haystack Bush 7  To elaborate a bit: Array-oriented languages (like J) consume the input and produce the output in toto. That is, all the results are produced simultaneously; consequently, throwing an exception for any part of the input would prohibit producing any output at all. And while it is both possible and simple to treat the input item by item, this is significantly slower and loses the great advantage of array processing. Therefore these languages generally produce a special, but conforming, output for "bad" inputs (in this case, an index past the end of the list). Then the functions which consume these outputs may be left untouched (as the special outputs are already in their domain) or may be extended simply. In this case, there is only one function which formats and prints the results, and its treatment of "good" and "bad" outputs is identical (it cannot distinguish the two). It is simply that the outputs of previous functions have been arranged such that the results are conformable. ## Java for Lists, they have an indexOf() method: import java.util.List; import java.util.Arrays; List<String> haystack = Arrays.asList("Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"); for (String needle : new String[]{"Washington","Bush"}) { int index = haystack.indexOf(needle); if (index < 0) System.out.println(needle + " is not in haystack"); else System.out.println(index + " " + needle); }  for arrays, you have to do it manually: import java.util.Arrays; String[] haystack = { "Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"}; for (String needle : new String[]{"Washington","Bush"}) { int index = Arrays.binarySearch(haystack, needle); if (index < 0) System.out.println(needle + " is not in haystack"); else System.out.println(index + " " + needle); }  Output: Washington is not in haystack 4 Bush  ## JavaScript var haystack = ['Zig', 'Zag', 'Wally', 'Ronald', 'Bush', 'Krusty', 'Charlie', 'Bush', 'Bozo'] var needles = ['Bush', 'Washington'] for (var i in needles) { var found = false; for (var j in haystack) { if (haystack[j] == needles[i]) { found = true; break; } } if (found) print(needles[i] + " appears at index " + j + " in the haystack"); else throw needles[i] + " does not appear in the haystack" }  The following Works with: JavaScript version 1.6 : for each (var needle in needles) { var idx = haystack.indexOf(needle); if (idx == -1) throw needle + " does not appear in the haystack" else print(needle + " appears at index " + idx + " in the haystack"); } // extra credit for each (var elem in haystack) { var first_idx = haystack.indexOf(elem); var last_idx = haystack.lastIndexOf(elem); if (last_idx > first_idx) { print(elem + " last appears at index " + last_idx + " in the haystack"); break } }  Or, generalising enough (in ES5) to allow for varying definitions of the type of match we are looking for: (function () { function findIndex(fnPredicate, list) { for (var i = 0, lng = list.length; i < lng; i++) { if (fnPredicate(list[i])) { return i; } } return Error("not found"); }; // DEFINING A PARTICULAR TYPE OF SEARCH MATCH function matchCaseInsensitive(s, t) { return s.toLowerCase() === t.toLowerCase(); } var lstHaystack = [ 'Zig', 'Zag', 'Wally', 'Ronald', 'Bush', 'Krusty', 'Charlie', 'Bush', 'Bozo' ], lstReversed = lstHaystack.slice(0).reverse(), iLast = lstHaystack.length - 1, lstNeedles = ['bush', 'washington']; return { 'first': lstNeedles.map(function (s) { return [s, findIndex(function (t) { return matchCaseInsensitive(s, t); }, lstHaystack)]; }), 'last': lstNeedles.map(function (s) { var varIndex = findIndex(function (t) { return matchCaseInsensitive(s, t); }, lstReversed); return [ s, typeof varIndex === 'number' ? iLast - varIndex : varIndex ]; }) } })();  Output: { "first": [ [ "bush", 4 ], [ "washington", "Error: not found" ] ], "last": [ [ "bush", 7 ], [ "washington", "Error: not found" ] ] }  ## jq The jq index origin is 0. The relevant methods for the tasks at hand are index/1 and rindex/1; indices/1 can also be used. In the following, the output is shown after the "# =>": ["a","b","c"] | index("b") # => 1 ["a","b","c","b"] | index("b") # => 1 ["a","b","c","b"] | index("x") // error("element not found") # => jq: error: element not found # Extra task - the last element of an array can be retrieved # using rindex/ or by using -1 as an index into the array produced by indices/1: ["a","b","c","b","d"] | rindex("b") # => 3 ["a","b","c","b","d"] | indices("b")[-1] # => 3 ## Julia Works with: Julia version 0.6 @show findfirst(["no", "?", "yes", "maybe", "yes"], "yes") @show indexin(["yes"], ["no", "?", "yes", "maybe", "yes"]) @show findin(["no", "?", "yes", "maybe", "yes"], ["yes"]) @show find(["no", "?", "yes", "maybe", "yes"] .== "yes")  Output: findfirst(["no", "?", "yes", "maybe", "yes"], "yes") = 3 indexin(["yes"], ["no", "?", "yes", "maybe", "yes"]) = [5] findin(["no", "?", "yes", "maybe", "yes"], ["yes"]) = [3, 5] find(["no", "?", "yes", "maybe", "yes"] .== "yes") = [3, 5] ## K  Haystack:("Zig";"Zag";"Wally";"Ronald";"Bush";"Krusty";"Charlie";"Bush";"Bozo") Needles:("Washington";"Bush") {:[y _in x;(y;x _bin y);(y;"Not Found")]}[Haystack]'Needles  Output: (("Washington" "Not Found") ("Bush" 4))  Additional: If more than one occurrence ("Bush"), also show position of the last occurrence. Here we use the dyadic verb _sm (string match) instead of _bin (binary search).  Haystack2: Haystack,,"Bush" Needles2:Needles,,"Zag" {+(x;{:[#&x;,/?(*&x;*|&x);"Not found"]}'+x _sm/:y)}[Needles2;Haystack2]  Output: (("Washington" "Not found") ("Bush" 4 9) ("Zag" 1))  ## Kotlin // version 1.0.6 (search_list.kt) fun main(args: Array<String>) { val haystack = listOf("Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag") println(haystack) var needle = "Zag" var index = haystack.indexOf(needle) val index2 = haystack.lastIndexOf(needle) println("\n'$needle' first occurs at index $index of the list") println("'$needle' last  occurs at index $index2 of the list\n") needle = "Donald" index = haystack.indexOf(needle) if (index == -1) throw Exception("$needle does not occur in the list")
}

Output:
[Zig, Zag, Wally, Ronald, Bush, Krusty, Charlie, Bush, Boz, Zag]

'Zag' first occurs at index 1 of the list
'Zag' last  occurs at index 9 of the list

Exception in thread "main" java.lang.Exception: Donald does not occur in the list
at Search_listKt.main(search_list.kt:13)


## Lang5

: haystack(*)  ['rosetta 'code 'search 'a 'list 'lang5 'code] find-index ;
: find-index
2dup eq length iota swap select swap drop
length if swap drop
else drop " is not in haystack" 2 compress "" join
then ;
: ==>search  apply ;

['hello 'code] 'haystack ==>search .
Output:
[ hello is not in haystack
[    1     6  ]
]

## Lasso

Lasso arrays have a findindex method which returns all matching indexes. [1]

local(haystack) = array('Zig', 'Zag', 'Wally', 'Ronald', 'Bush', 'Krusty', 'Charlie', 'Bush', 'Bozo')

#haystack->findindex('Bush')->first // 5
#haystack->findindex('Bush')->last // 8

protect => {^
handle_error => {^ error_msg ^}
fail_if(not #haystack->findindex('Washington')->first,'Washington is not in haystack.')
^}

Output:
5
8
Washington is not in haystack.

## Lingo

haystack = ["apples", "oranges", "bananas", "oranges"]
needle = "oranges"

pos = haystack.getPos(needle)
if pos then
put "needle found at index "&pos
else
end if

-- "needle found at index 2"

## Lisaac

+ haystack : ARRAY[STRING];
haystack := "Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo".split;
"Washington Bush".split.foreach { needle : STRING;
haystack.has(needle).if {
haystack.first_index_of(needle).print;
' '.print;
needle.print;
'\n'.print;
} else {
needle.print;
" is not in haystack\n".print;
};
};

## Logo

to indexof :item :list
if empty? :list [(throw "NOTFOUND 0)]
if equal? :item first :list [output 1]
output 1 + indexof :item butfirst :list
end

to showindex :item :list
make "i catch "NOTFOUND [indexof :item :list]
ifelse :i = 0 [(print :item [ not found in ] :list)] [(print :item [ found at position ] :i [ in ] :list)]
end

showindex "dog [My dog has fleas]   ; dog found at position 2 in My dog has fleas
showindex "cat [My dog has fleas]   ; cat not found in My dog has fleas

## Lua

list = {"mouse", "hat", "cup", "deodorant", "television", "soap", "methamphetamine", "severed cat heads"} --contents of my desk

for i,v in ipairs(list)
if v == item then print(i) end
end


## M2000 Interpreter

Example based on BASIC's example, changed to find only first occurrence, and last if a second exist. We make one inventory queue which can take sane keys, and a second one with all keys in reverse order. Search works with hash table inside inventory. Normally we use Exist(inventoryA, "key") and if it is true then we get the value as Eval(inventoryA) without using second search, by temporary use of an index. We can read that index by making a variable to bind a property of COM object (the object under the inventory).

Module Checkit {
Flush ' empty stack
Inventory Queue Haystack=  "foo", "bar", "baz", "quux", "quuux", "quuuux", "bazola", "ztesch", "foo", "bar", "thud", "grunt"
Append  Haystack, "foo", "bar", "bletch", "foo", "bar", "fum", "fred", "jim", "sheila", "barney", "flarp", "zxc"
Append  Haystack,  "spqr", "wombat", "shme", "foo", "bar", "baz", "bongo", "spam", "eggs", "snork", "foo", "bar"
Append  Haystack,  "zot", "blarg", "wibble", "toto", "titi", "tata", "tutu", "pippo", "pluto", "paperino", "aap"
Append  Haystack,  "noot", "mies", "oogle", "foogle", "boogle", "zork", "gork", "bork"
\\ Inventories are objects and we have access to properties using COM model
With HayStack, "index" as index
Inventory Queue HayStackRev
N=Each(HayStack, -1, 1)
While N {
Append HayStackRev, Eval$(N, N^) } With HayStackRev, "index" as indexRev Print Len(HayStack) Print Len(HayStackRev) local needle$
\\ Print all elements using columns
Print haystack
Repeat {
Input "Word to search for? (Leave blank to exit) ", needle$If needle$ <> "" Then {
If Exist(haystackrev,lcase$(needle$) ) Then {
Print "Found "; CHR$(34); needle$; CHR$(34); " at index "; STR$(len(haystackrev)-indexrev,"")

If Exist(haystack,lcase$(needle$) ) Then  {
if len(haystackrev)-1<>indexrev+index then {
Print "Found "; CHR$(34); needle$; CHR$(34); " at index "; STR$(Len(haystack)-index,"")
}
}
} Else  Print CHR$(34); needle$; CHR$(34); " not found" } Else Exit } Always } CheckIt Extra-Extra: Find all occurrences displaying the indexes for each one. Module CheckThis { Inventory Queue Haystack= "foo", "bar", "baz", "quux", "quuux", "quuuux", "bazola", "ztesch", "foo", "bar", "thud", "grunt" Append Haystack, "foo", "bar", "bletch", "foo", "bar", "fum", "fred", "jim", "sheila", "barney", "flarp", "zxc" Append Haystack, "spqr", "wombat", "shme", "foo", "bar", "baz", "bongo", "spam", "eggs", "snork", "foo", "bar" Append Haystack, "zot", "blarg", "wibble", "toto", "titi", "tata", "tutu", "pippo", "pluto", "paperino", "aap" Append Haystack, "noot", "mies", "oogle", "foogle", "boogle", "zork", "gork", "bork" \\ Print all list Print Haystack \\ inventory queue can get same keys \\ inventory use hashtable. \\ Inventory put same keys in a linked list, so we can found easy Do Input "Word to search for? (Leave blank press enter to exit) ", needle$
if needle$="" then exit n=1 s$=lcase$(needle$)
While exist(Haystack, s$, n) \\ number, key and position (zero based convert to one based) Print n, Eval$(HayStack!), Eval(HayStack!)+1
n++
End While
If n=1 Then Print needle$;" not found" Always } CheckThis ## Maple haystack := ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"]: occurences := ListTools:-SearchAll(needle,haystack): try #first occurence printf("The first occurence is at index %d\n", occurences[1]); #last occurence, note that StringTools:-SearchAll()retuns a list of all occurences positions printf("The last occurence is at index %d\n", occurences[-1]); catch : print("Erros: Needle not found in the haystack"): end try: Examples: needle := "Washington": "Needle not found in the haystack" needle := "Bush": The first occurence is at index 5 The last occurence is at index 8 ## Mathematica/Wolfram Language This examples shows you the first appearance, the last appearance, and all appearances (as a list): haystack = {"Zig","Zag","Wally","Ronald","Bush","Zig","Zag","Krusty","Charlie","Bush","Bozo"}; needle = "Zag"; first = Position[haystack,needle,1][[1,1]] last = Position[haystack,needle,1][[-1,1]] all = Position[haystack,needle,1][[All,1]]  gives back: 2 7 {2,7}  ## MATLAB Collections of strings are stored in cell arrays in MATLAB. The solution bellow will only work for a cell array of this construction: stringCollection = {'string1','string2',...,'stringN'}  It will not work for any other construction, for example: stringCollection = {{'string1'},{'string2'},{...},{'stringN'}}  searchCollection.m: function index = searchCollection(list,searchItem,firstLast) %firstLast is a string containing either 'first' or 'last'. The 'first' %flag will cause searchCollection to return the index of the first %instance of the item being searched. 'last' will cause %searchCollection to return the index of the last instance of the item %being searched. indicies = cellfun(@(x)x==searchItem,list); index = find(indicies,1,firstLast); assert(~isempty(index),['The string ''' searchItem ''' does not exist in this collection of strings.']); end  Output: >> list = {'a','b','c','d','e','c','f','c'}; >> searchCollection(list,'c','first') ans = 3 >> searchCollection(list,'c','last') ans = 8 >> searchCollection(list,'g','last') ??? Error using ==> searchCollection at 11 The string 'g' does not exist in this collection of strings.  ## Maxima haystack: ["Zig","Zag","Wally","Ronald","Bush","Zig","Zag","Krusty","Charlie","Bush","Bozo"]; needle: "Zag"; findneedle(needle, haystack, [opt]):=block([idx], idx: sublist_indices(haystack, lambda([w], w=needle)), if emptyp(idx) then throw('notfound), if emptyp(opt) then return(idx), opt: first(opt), if opt='f then first(idx) else if opt='l then last(idx) else throw('unknownmode));  Usage: (%i32) catch(findneedle("Zag", haystack, 'f)); (%o32) 2 (%i33) catch(findneedle("Zag", haystack, 'l)); (%o33) 7 (%i34) catch(findneedle("Washington", haystack)); (%o34) notfound (%i35) catch(findneedle("Bush", haystack, 'f)); (%o35) 5 (%i36) catch(findneedle("Zag", haystack)); (%o36) [2, 7] (%i37) catch(findneedle("Zag", haystack, 'l)); (%o37) 7 ## MAXScript haystack=#("Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo") for needle in #("Washington","Bush") do ( index = findItem haystack needle if index == 0 then ( format "% is not in haystack\n" needle ) else ( format "% %\n" index needle ) ) Output: Washington is not in haystack 5 Bush ## Nanoquery Translation of: Python $haystack = list()
append $haystack "Zig" "Zag" "Wally" "Ronald" "Bush" "Krusty" "Charlie" append$haystack "Bush" "Bozo"

$needles = list() append$needles "Washington"
append $needles "Bush" for ($i = 0) ($i < len($needles)) ($i =$i + 1)
$needle =$needles[$i] try // use array lookup syntax to get the index of the needle println$haystack[$needle] + " " +$needle
catch
println $needle + " is not in haystack" end end for Output: Washington is not in haystack 4 Bush ## NetRexx /* NetRexx */ options replace format comments java crossref symbols nobinary driver(arg) -- call the test wrapper return -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method searchListOfWords(haystack, needle, forwards = (1 == 1), respectCase = (1 == 1)) public static signals Exception if \respectCase then do needle = needle.upper() haystack = haystack.upper() end if forwards then wp = haystack.wordpos(needle) else wp = haystack.words() - haystack.reverse().wordpos(needle.reverse()) + 1 if wp = 0 then signal Exception('*** Error! "'needle'" not found in list ***') return wp -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method searchIndexedList(haystack, needle, forwards = (1 == 1), respectCase = (1 == 1)) public static signals Exception if forwards then do strtIx = 1 endIx = haystack[0] incrIx = 1 end else do strtIx = haystack[0] endIx = 1 incrIx = -1 end wp = 0 loop ix = strtIx to endIx by incrIx if respectCase then if needle == haystack[ix] then wp = ix else nop else if needle.upper() == haystack[ix].upper() then wp = ix else nop if wp > 0 then leave ix end ix if wp = 0 then signal Exception('*** Error! "'needle'" not found in indexed list ***') return wp -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- Test wrapper method driver(arg) public static -- some manifests TRUE_ = (1 == 1); FALSE_ = \TRUE_ FORWARDS_ = TRUE_; BACKWARDS_ = FALSE_ CASERESPECT_ = TRUE_; CASEIGNORE_ = \CASERESPECT_ -- test data needles = ['barley', 'quinoa'] -- a simple list of words. Lists of words are indexable in NetRexx via the word(N) function hayrick = 'Barley maize barley sorghum millet wheat rice rye barley Barley oats flax' -- a Rexx indexed string made up from the words in hayrick cornstook = '' loop w_ = 1 to hayrick.words() -- populate the indexed string cornstook[0] = w_ cornstook[w_] = hayrick.word(w_) end w_ loop needle over needles do -- process the list of words say 'Searching for "'needle'" in the list "'hayrick'"' idxF = searchListOfWords(hayrick, needle) idxL = searchListOfWords(hayrick, needle, BACKWARDS_) say ' The first occurence of "'needle'" is at index' idxF 'in the list' say ' The last occurence of "'needle'" is at index' idxL 'in the list' idxF = searchListOfWords(hayrick, needle, FORWARDS_, CASEIGNORE_) idxL = searchListOfWords(hayrick, needle, BACKWARDS_, CASEIGNORE_) say ' The first caseless occurence of "'needle'" is at index' idxF 'in the list' say ' The last caseless occurence of "'needle'" is at index' idxL 'in the list' say catch ex = Exception say ' 'ex.getMessage() say end do -- process the indexed list corn = '' loop ci = 1 to cornstook[0] corn = corn cornstook[ci] end ci say 'Searching for "'needle'" in the indexed list "'corn.space()'"' idxF = searchIndexedList(cornstook, needle) idxL = searchIndexedList(cornstook, needle, BACKWARDS_) say ' The first occurence of "'needle'" is at index' idxF 'in the indexed list' say ' The last occurence of "'needle'" is at index' idxL 'in the indexed list' idxF = searchIndexedList(cornstook, needle, FORWARDS_, CASEIGNORE_) idxL = searchIndexedList(cornstook, needle, BACKWARDS_, CASEIGNORE_) say ' The first caseless occurence of "'needle'" is at index' idxF 'in the indexed list' say ' The last caseless occurence of "'needle'" is at index' idxL 'in the indexed list' say catch ex = Exception say ' 'ex.getMessage() say end end needle return Output: Searching for "barley" in the list "Barley maize barley sorghum millet wheat rice rye barley Barley oats flax" The first occurence of "barley" is at index 3 in the list The last occurence of "barley" is at index 9 in the list The first caseless occurence of "barley" is at index 1 in the list The last caseless occurence of "barley" is at index 10 in the list Searching for "barley" in the indexed list "Barley maize barley sorghum millet wheat rice rye barley Barley oats flax" The first occurence of "barley" is at index 3 in the indexed list The last occurence of "barley" is at index 9 in the indexed list The first caseless occurence of "barley" is at index 1 in the indexed list The last caseless occurence of "barley" is at index 10 in the indexed list Searching for "quinoa" in the list "Barley maize barley sorghum millet wheat rice rye barley Barley oats flax" *** Error! "quinoa" not found in list *** Searching for "quinoa" in the indexed list "Barley maize barley sorghum millet wheat rice rye barley Barley oats flax" *** Error! "quinoa" not found in indexed list ***  ## Nim let haystack = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"] for needle in ["Bush", "Washington"]: let f = haystack.find(needle) if f >= 0: echo f, " ", needle else: raise newException(ValueError, needle & " not in haystack")  Output: 4 Bush [...]/search_a_list.nim(8) search_a_list Error: unhandled exception: Washington not in haystack [ValueError] ## Objeck use Collection; class Test { function : Main(args : String[]) ~ Nil { haystack := ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"]; values := CompareVector->New(); each(i : haystack) { values->AddBack(haystack[i]->As(Compare)); }; needles := ["Washington", "Bush"]; each(i : needles) { values->Has(needles[i]->As(Compare))->PrintLine(); }; } } ## Objective-C Works with: Objective-C version 2.0+ NSArray *haystack = @[@"Zig",@"Zag",@"Wally",@"Ronald",@"Bush",@"Krusty",@"Charlie",@"Bush",@"Bozo"]; for (id needle in @[@"Washington",@"Bush"]) { int index = [haystack indexOfObject:needle]; if (index == NSNotFound) NSLog(@"%@ is not in haystack", needle); else NSLog(@"%i %@", index, needle); }  ## OCaml # let find_index pred lst = let rec loop n = function [] -> raise Not_found | x::xs -> if pred x then n else loop (n+1) xs in loop 0 lst;; val find_index : ('a -> bool) -> 'a list -> int = <fun> # let haystack = ["Zig";"Zag";"Wally";"Ronald";"Bush";"Krusty";"Charlie";"Bush";"Bozo"];; val haystack : string list = ["Zig"; "Zag"; "Wally"; "Ronald"; "Bush"; "Krusty"; "Charlie"; "Bush"; "Bozo"] # List.iter (fun needle -> try Printf.printf "%i %s\n" (find_index ((=) needle) haystack) needle with Not_found -> Printf.printf "%s is not in haystack\n" needle) ["Washington"; "Bush"];; Washington is not in haystack 4 Bush - : unit = ()  ## Odin package main import "core:slice" import "core:fmt" main :: proc() { hay_stack := []string{"Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"} // Odin does not support exceptions. // For conditions requiring special processing during the execution of a program it is // encouraged to make that explicit through return values: index, found := slice.linear_search(hay_stack, "Bush") if found do fmt.printf("First occurence of 'Bush' at %d\n", index) index, found = slice.linear_search(hay_stack, "Rob") if found do fmt.printf("First occurence of 'Rob' at %d\n", index) } // Output: // First occurence of 'Bush' at 4  ## Oforth indexOf returns null if an object is not into a collection, not an exception. : needleIndex(needle, haystack) haystack indexOf(needle) dup ifNull: [ drop ExRuntime throw("Not found", needle) ] ; [ "Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz" ] const: Haystack needleIndex("Bush", Haystack) println Haystack lastIndexOf("Bush") println needleIndex("Washington", Haystack) println Output: 5 8 [1:interpreter] ExRuntime : Not found <Washington>  ## ooRexx All ooRexx collections support an index method that will search for an item. For ordered collections, this will always be the first item. For unordered collections, the index returned is undetermined. -- ordered collections always return the first hit a = .array~of(1,2,3,4,4,5) say a~index(4) a2 = .array~new(5,5) -- multidimensional a2[3,3] = 4 -- the returned index is an array of values say a2~index(4)~makestring('line', ',') -- Note, list indexes are assigned when an item is added and -- are not tied to relative position l = .list~of(1,2,3,4,4,5) say l~index(4) q = .queue~of(1,2,3,4,4,5) say q~index(4) -- directories are unordered, so it is -- undertermined which one is returned d = .directory~new d["foo"] = 4 d["bar"] = 4 say d~index(4) ## Oz No such function exists for the built-in list type (the operation is quite inefficient, after all). A possible implementation: declare %% Lazy list of indices of Y in Xs. fun {Indices Y Xs} for X in Xs I in 1;I+1 yield:Yield do if Y == X then {Yield I} end end end fun {Index Y Xs} case {Indices Y Xs} of X|_ then X else raise index(elementNotFound Y) end end end Haystack = ["Zig" "Zag" "Wally" "Ronald" "Bush" "Krusty" "Charlie" "Bush" "Bozo"] in {Show {Index "Bush" Haystack}} {Show {List.last {Indices "Bush" Haystack}}} {Show {Index "Washington" Haystack}} %% throws ## PARI/GP Works with: PARI/GP version 2.4.3 and above find(v,n)={ my(i=setsearch(v,n)); if(i, while(i>1, if(v[i-1]==n,i--)) , error("Could not find") ); i }; ## Pascal See Delphi ## Perl use List::Util qw(first); my @haystack = qw(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo); foreach my$needle (qw(Washington Bush)) {
my $index = first {$haystack[$_] eq$needle } (0 .. $#haystack); # note that "eq" was used because we are comparing strings # you would use "==" for numbers if (defined$index) {
print "$index$needle\n";
} else {
print "$needle is not in haystack\n"; } }  Output: Washington is not in haystack 4 Bush  You could install a non-standard module List::MoreUtils: use List::MoreUtils qw(first_index); my @haystack = qw(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo); foreach my$needle (qw(Washington Bush)) {
my $index = first_index {$_ eq $needle } @haystack; # note that "eq" was used because we are comparing strings # you would use "==" for numbers if (defined$index) {
print "$index$needle\n";
} else {
print "$needle is not in haystack\n"; } }  Alternatively, if you need to do this a lot, you could create a hash table mapping values to indices in the haystack: my @haystack = qw(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo); my %haystack_indices; @haystack_indices{ @haystack } = (0 ..$#haystack); # Caution: this finds the largest index, not the smallest

foreach my $needle (qw(Washington Bush)) { my$index = $haystack_indices{$needle};
if (defined $index) { print "$index $needle\n"; } else { print "$needle is not in haystack\n";
}
}

Output:
Washington is not in haystack
7 Bush


## Phix

Library: Phix/basics
constant s = {"Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"}

integer r = find("Zag",s)       ?r  -- 2    (first)
r = find("Zag",s,r+1)           ?r  -- 10   (next)
r = find("Zag",s,r+1)           ?r  -- 0    (no more)
r = rfind("Zag",s)              ?r  -- 10   (last)
r = find("Zog",s)               ?r  -- 0    (none)


## Phixmonti

"mouse" "hat" "cup" "deodorant" "television"
"soap" "methamphetamine" "severed cat heads" "cup"
pstack
stklen tolist reverse
0 tolist var t

"Enter string to search: " input var s nl
true
while
len t swap 0 put var t
endif
tail nip len
endwhile
drop

t len not if
else
reverse
"First index for " print s print " : " print 1 get print
len 1 > if
nl "Last index for " print s print " : " print len get print
endif
endif
drop

Other solution with syntactic sugar for list construction.

include Utilitys.pmt

0 var acum
0 var p
"Zag" var word

def search
word find var p p
enddef

( "Zig" "Zag" "Wally" "Ronald" "Bush" "Krusty" "Charlie" "Bush" "Boz" "Zag" )

dup print nl nl

search
while
p acum + var acum
( word " located in position " acum ) lprint nl
len p - p 1 + swap slice nip
search
endwhile

## PHP

$haystack = array("Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"); foreach (array("Washington","Bush") as$needle) {
$i = array_search($needle, $haystack); if ($i === FALSE) // note: 0 is also considered false in PHP, so you need to specifically check for FALSE
echo "$needle is not in haystack\n"; else echo "$i $needle\n"; }  Output: Washington is not in haystack 4 Bush  ## Picat Picat has built-in functions find_first_of/2 and find_last_of/2. They return -1 if the needle is not found, so here they are wrapped in functions that throws exceptions in this case. And Picat is 1-based. import util. go => Haystack=["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Bush", "Charlie", "Bush", "Boz", "Zag"], println("First 'Bush'"=search_list(Haystack,"Bush")), println("Last 'Bush'"=search_list_last(Haystack,"Bush")), println("All 'Bush'"=search_list_all(Haystack,"Bush")), catch(WaldoIx=search_list(Haystack,"Waldo"),E,println(E)), println("Waldo"=WaldoIx), nl. % Wrapping find_first_of/2 and find_last_of/2 with exceptions search_list(Haystack,Needle) = Ix => Ix = find_first_of(Haystack,Needle), if Ix < 0 then throw$error(search_list(Needle),not_found)
end.

search_list_last(Haystack,Needle) = Ix =>
Ix = find_last_of(Haystack,Needle),
if Ix < 0 then
throw $error(search_list_last(Needle),not_found) end. % Find all indices search_list_all(Haystack,Needle) = Ixs => Ixs = [Ix : {W,Ix} in zip(Haystack,1..Haystack.len), W == Needle], if Ixs == [] then throw$error(search_list_all(Needle),not_found)
end.
Output:
First 'Bush' = 5
Last 'Bush' = 9
All 'Bush' = [5,7,9]
error(search_list(Waldo),not_found)
Waldo = _3590

## PicoLisp

Note that in PicoLisp all indexes are one-based (the first element has the position '1')

(de lastIndex (Item Lst)
(- (length Lst) (index Item (reverse Lst)) -1) )

(de findNeedle (Fun Sym Lst)

(let Lst '(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo)
(findNeedle index 'Washington Lst)
(findNeedle index 'Bush Lst)
(findNeedle lastIndex 'Bush Lst) )
Output:
Washington not found
Bush 5
Bush 8

## PL/I

search: procedure () returns (fixed binary);
declare haystack (0:9) character (200) varying static initial
('apple', 'banana', 'celery', 'dumpling', 'egg', 'flour',
'grape', 'pomegranate', 'raisin', 'sugar' );
declare needle character (200) varying;
declare i fixed binary;
declare missing_needle condition;

on condition(missing_needle) begin;
put skip list ('your string ''' || needle ||
''' does not exist in the haystack.');
end;

get edit (needle) (L);
do i = lbound(haystack,1) to hbound(haystack,1);
if needle = haystack(i) then return (i);
end;
signal condition(missing_needle);
return (lbound(haystack,1)-1);
end search;

## Plain English

To run:
Start up.
Make an example haystack.
Find "b" in the example haystack giving a count.
Destroy the example haystack.
Write "The index of ""b"" is " then the count on the console.
Wait for the escape key.
Shut down.

A needle is a string.

Some hay is some strings.

A bale is a thing with some hay.

A haystack is some bales.

To add some hay to a haystack:
Allocate memory for a bale.
Put the hay into the bale's hay.
Append the bale to the haystack.

To make an example haystack:
Add "a" to the example haystack.
Add "a" to the example haystack.
Add "b" to the example haystack.
Add "c" to the example haystack.
Add "d" to the example haystack.

\ As Plain English doesn't have exceptions, return -1 if the needle is not found.
To find a needle in a haystack giving a count:
Get a bale from the haystack.
Loop.
If the bale is nil, put -1 into the count; exit.
If the bale's hay is the needle, exit.
Put the bale's next into the bale.
Bump the count.
Repeat.
Output:
The index of "b" is 2


## PowerShell

Works with: PowerShell version 4.0
function index($haystack,$needle) {
$index =$haystack.IndexOf($needle) if($index -eq -1) {
Write-Warning "$needle is absent" } else {$index
}

}
$haystack = @("word", "phrase", "preface", "title", "house", "line", "chapter", "page", "book", "house") index$haystack "house"
index $haystack "paragraph"  Output: 4 WARNING: paragraph is absent  ### PowerShell Extra credit The -Verbose switch is available to any advanced function. function Find-Needle { [CmdletBinding()] [OutputType([int])] Param ( [Parameter(Mandatory=$true, Position=0)]
[string]
$Needle, [Parameter(Mandatory=$true, Position=1)]
[string[]]
$Haystack, [switch]$LastIndex
)

if ($LastIndex) {$index = [Array]::LastIndexOf($Haystack,$Needle)

if ($index -eq -1) { Write-Verbose "Needle not found in Haystack" return$index
}

if ((($Haystack | Group-Object | Where-Object Count -GT 1).Group).IndexOf($Needle) -ne -1)
{
Write-Verbose "Last needle found in Haystack at index $index" } else { Write-Verbose "Needle found in Haystack at index$index  (No duplicates were found)"
}

return $index } else {$index = [Array]::IndexOf($Haystack,$Needle)

if ($index -eq -1) { Write-Verbose "Needle not found in Haystack" } else { Write-Verbose "Needle found in Haystack at index$index"
}

return $index } }$haystack = @("word", "phrase", "preface", "title", "house", "line", "chapter", "page", "book", "house")

Find-Needle "house" $haystack  Output: 4  Find-Needle "house"$haystack -Verbose

Output:
VERBOSE: Needle found in Haystack at index 4
4

Find-Needle "house" $haystack -LastIndex -Verbose  Output: VERBOSE: Last needle found in Haystack at index 9 9  Find-Needle "title"$haystack -LastIndex -Verbose

Output:
VERBOSE: Needle found in Haystack at index 3  (No duplicates were found)
3

Find-Needle "something" $haystack -Verbose  Output: VERBOSE: Needle not found in Haystack -1  ## Prolog Works with SWI-Prolog search_a_list(N1, N2) :- L = ["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"], write('List is :'), maplist(my_write, L), nl, nl, ( nth1(Ind1, L, N1) -> format('~s is in position ~w~n', [N1, Ind1]) ; format('~s is not present~n', [N1])), ( nth1(Ind2, L, N2) -> format('~s is in position ~w~n', [N2, Ind2]) ; format('~s is not present~n', [N2])), ( reverse_nth1(Ind3, L, N1) -> format('~s last position is ~w~n', [N1, Ind3]) ; format('~s is not present~n', [N1])). reverse_nth1(Ind, L, N) :- reverse(L, RL), length(L, Len), nth1(Ind1, RL, N), Ind is Len - Ind1 + 1. my_write(Name) :- writef(' %s', [Name]).  Output:  ?- search_a_list("Zag", "Simpson"). List is : Zig Zag Wally Ronald Bush Krusty Charlie Bush Boz Zag Zag is in position 2 Simpson is not present Zag last position is 10 true.  ## Python haystack=["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"] for needle in ("Washington","Bush"): try: print haystack.index(needle), needle except ValueError, value_error: print needle,"is not in haystack"  Output: Washington is not in haystack 4 Bush  Note that in Python, the index method of a list already raises an exception. The following shows the default information given when the exception is not captured in the program: >>> haystack=["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"] >>> haystack.index('Bush') 4 >>> haystack.index('Washington') Traceback (most recent call last): File "<pyshell#95>", line 1, in <module> haystack.index('Washington') ValueError: list.index(x): x not in list >>>  There is no built-in method for returning the highest index of a repeated string in a Python list, tuple or array, (although strings have rindex). Instead we need to look for the index in the reversed list and adjust the result. >>> def hi_index(needle, haystack): return len(haystack)-1 - haystack[::-1].index(needle) >>> # Lets do some checks >>> for n in haystack: hi = hi_index(n, haystack) assert haystack[hi] == n, "Hi index is of needle" assert n not in haystack[hi+1:], "No higher index exists" if haystack.count(n) == 1: assert hi == haystack.index(n), "index == hi_index if needle occurs only once" >>>  ## R find.needle <- function(haystack, needle="needle", return.last.index.too=FALSE) { indices <- which(haystack %in% needle) if(length(indices)==0) stop("no needles in the haystack") if(return.last.index.too) range(indices) else min(indices) }  Example usage: haystack1 <- c("where", "is", "the", "needle", "I", "wonder") haystack2 <- c("no", "sewing", "equipment", "in", "here") haystack3 <- c("oodles", "of", "needles", "needles", "needles", "in", "here") find.needle(haystack1) # 4 find.needle(haystack2) # error find.needle(haystack3) # 3 find.needle(haystack3, needle="needles", ret=TRUE) # 3 5  ## Racket The function index returns the index of the the element x in the sequence xs. If the element is not found, then #f is returned. (define (index xs y) (for/first ([(x i) (in-indexed xs)] #:when (equal? x y)) i))  If the last index of an element is needed, for/last is used: (define (index-last xs y) (for/last ([(x i) (in-indexed xs)] #:when (equal? x y)) i))  Both index and index-last can handle any sequence such as lists, vectors, sets etc. Let us test with a linked list: (define haystack '("Zig" "Zag" "Wally" "Ronald" "Bush" "Krusty" "Charlie" "Bush" "Bozo")) (for/list ([needle '("Bender" "Bush")]) (index haystack needle)) (for/list ([needle '("Bender" "Bush")]) (index-last haystack needle))  Output: '(#f 4) '(#f 7)  ## Raku (formerly Perl 6) Works with: Rakudo Star version 2016.07 my @haystack = <Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo>; for <Washington Bush> ->$needle {
say "$needle -- { @haystack.first($needle, :k) // 'not in haystack' }";
}

Output:
Washington -- not in haystack
Bush -- 4


Or, including the "extra credit" task:

Works with: Rakudo Star version 2016.07
my Str @haystack = <Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo>;

for <Washingston Bush> -> $needle { my$first = @haystack.first($needle, :k); if defined$first {
my $last = @haystack.first($needle, :k, :end);
say "$needle -- first at$first, last at $last"; } else { say "$needle -- not in haystack";
}
}

Output:
Washingston -- not in haystack
Bush -- first at 4, last at 7


The built-in method .first takes a smart-matcher, and returns the first matching list element.
The :k adverb tells it to return the key (a.k.a. list index) instead of the value of the matching element.
The :end adverb tells it to start searching from the end of the list.

If you plan to do many searches on the same large list, you might want to build a search hash first for efficient look-up:

my @haystack = <Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo>;

my %index;
%index{.value} //= .key for @haystack.pairs;

for <Washington Bush> -> $needle { say "$needle -- { %index{$needle} // 'not in haystack' }"; }  ## REBOL REBOL [ Title: "List Indexing" URL: http://rosettacode.org/wiki/Index_in_a_list ] locate: func [ "Find the index of a string (needle) in string collection (haystack)." haystack [series!] "List of values to search." needle [string!] "String to find in value list." /largest "Return the largest index if more than one needle." /local i ][ i: either largest [ find/reverse tail haystack needle][find haystack needle] either i [return index? i][ throw reform [needle "is not in haystack."] ] ] ; Note that REBOL uses 1-base lists instead of 0-based like most ; computer languages. Therefore, the index provided will be one ; higher than other results on this page. haystack: parse "Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo" none print "Search for first occurance:" foreach needle ["Washington" "Bush"] [ print catch [ reform [needle "=>" locate haystack needle] ] ] print [crlf "Search for last occurance:"] foreach needle ["Washington" "Bush"] [ print catch [ reform [needle "=>" locate/largest haystack needle] ] ]  Output: Search for first occurance: Washington is not in haystack. Bush => 5 Search for last occurance: Washington is not in haystack. Bush => 8 ## REXX ### version 1 This REXX program searches a collection of string (haystack) that are stored in a sequential REXX array. No counter is kept of the number of items, but they should be numbered consecutively and can't have any gaps. The haystack items may have any character, including blanks. A null value isn't allowed in this method of representing values. /*REXX program searches a collection of strings (an array of periodic table elements).*/ hay.= /*initialize the haystack collection. */ hay.1 = 'sodium' hay.2 = 'phosphorous' hay.3 = 'californium' hay.4 = 'copernicium' hay.5 = 'gold' hay.6 = 'thallium' hay.7 = 'carbon' hay.8 = 'silver' hay.9 = 'curium' hay.10 = 'copper' hay.11 = 'helium' hay.12 = 'sulfur' needle = 'gold' /*we'll be looking for the gold. */ upper needle /*in case some people capitalize stuff.*/ found=0 /*assume the needle isn't found yet. */ do j=1 while hay.j\=='' /*keep looking in the haystack. */ _=hay.j; upper _ /*make it uppercase to be safe. */ if _=needle then do; found=1 /*we've found the needle in haystack. */ leave /* ··· and stop looking, of course. */ end end /*j*/ if found then return j /*return the haystack index number. */ else say needle "wasn't found in the haystack!" return 0 /*indicates the needle wasn't found. */  ### version 2 This REXX program searches a collection of string (haystack) that are stored in a REXX array (which may have gaps). A safe counter is kept of the maximum (highest) index in the array, this counter may be any sufficiently high number. The array may be out of order (but not recommended!). /*REXX program searches a collection of strings (an array of periodic table elements).*/ hay.0 = 1000 /*safely indicate highest item number. */ hay.200 = 'Binilnilium' hay.98 = 'californium' hay.6 = 'carbon' hay.112 = 'copernicium' hay.29 = 'copper' hay.114 = 'flerovium' hay.79 = 'gold' hay.2 = 'helium' hay.1 = 'hydrogen' hay.82 = 'lead' hay.116 = 'livermorium' hay.15 = 'phosphorous' hay.47 = 'silver' hay.11 = 'sodium' hay.16 = 'sulfur' hay.81 = 'thallium' hay.92 = 'uranium' /* [↑] sorted by the element name. */ needle = 'gold' /*we'll be looking for the gold. */ upper needle /*in case some people capitalize. */ found=0 /*assume the needle isn't found (yet).*/ do j=1 for hay.0 /*start looking in haystack, item 1. */ _=hay.j; upper _ /*make it uppercase just to be safe. */ if _=needle then do; found=1 /*we've found the needle in haystack. */ leave /* ··· and stop looking, of course. */ end end /*j*/ if found then return j /*return the haystack index number. */ else say needle "wasn't found in the haystack!" return 0 /*indicates the needle wasn't found. */ ### version 3 This REXX program searches a collection of string (haystack) that are stored in a REXX array. This form uses a type of array called a sparse array (with non-numeric indexes). One drawback of this approach is that the items can't have leading/trailing/imbedded blanks, nor can they have special characters. Only letters, numerals, and a few special characters are allowed: !, @, #,$,   ?,   and   _.

This method (finding a needle in a haystack) is extremely fast as there isn't any
table look-up, the "finding" is done by REXX's own internal method of variable lookup,
and, for the most part, it based on a table hashing algorithm.

This method pre-prends an underscore (underbar) to avoid collision with any REXX
variable names. Therefore, there shouldn't be any REXX variable names (in this
program) that have a leading underscore   (_).

/*REXX program searches a collection of strings   (an array of periodic table elements).*/
hay.=0                                           /*initialize the haystack collection.  */
hay._sodium       = 1
hay._phosphorous  = 1
hay._californium  = 1
hay._copernicium  = 1
hay._gold         = 1
hay._thallium     = 1
hay._carbon       = 1
hay._silver       = 1
hay._copper       = 1
hay._helium       = 1
hay._sulfur       = 1
/*underscores (_) are used to NOT ...  */
/*   ... conflict with variable names. */

needle  = 'gold'                                 /*we'll be looking for the gold.       */

Xneedle = '_'needle                              /*prefix an underscore (_)  character. */
upper Xneedle                                    /*uppercase:  how REXX stores them.    */

/*alternative version of above:        */
/*       Xneedle=translate('_'needle)  */

found=hay.Xneedle                                /*this is it, it's found (or maybe not)*/

if found  then return j                          /*return the haystack  index  number.  */
else say  needle  "wasn't found in the haystack!"
return 0                                         /*indicates the needle  wasn't  found. */

### version 4

This method uses a simple string (so haystack items can't have embedded blanks or tabs in them).
Code was added to uppercase both the   haystack   and the   needle   to make the search   case insensitive.

/*REXX program searches a collection of strings   (an array of periodic table elements).*/
/*───────────────names of the first 200 elements of the periodic table.─────────────*/
_=  'hydrogen helium lithium beryllium boron carbon nitrogen oxygen fluorine neon sodium'
_=_ 'magnesium aluminum silicon phosphorous sulfur chlorine argon potassium calcium'
_=_ 'scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc'
_=_ 'gallium germanium arsenic selenium bromine krypton rubidium strontium yttrium'
_=_ 'indium tin antimony tellurium iodine xenon cesium barium lanthanum cerium'
_=_ 'praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium'
_=_ 'holmium erbium thulium ytterbium lutetium hafnium tantalum tungsten rhenium osmium'
_=_ 'francium radium actinium thorium protactinium uranium neptunium plutonium americium'
_=_ 'curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium'
_=_ 'rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium'
_=_ 'roentgenium copernicium nihonium flerovium moscovium livermorium tennessine'
_=_ 'oganesson ununennium unbinilium unbiunium unbibium unbitrium unbiquadium'
_=_ 'unbipentium unbihexium unbiseptium unbioctium unbiennium untrinilium untriunium'
_=_ 'untribium untritrium untriquadium untripentium untrihexium untriseptium untrioctium'
_=_ 'unpentunium unpentbium unpenttrium unpentquadium unpentpentium unpenthexium'
_=_ 'unpentseptium unpentoctium unpentennium unhexnilium unhexunium unhexbium unhextrium'
_=_ 'unhexquadium unhexpentium unhexhexium unhexseptium unhexoctium unhexennium'
_=_ 'unseptnilium unseptunium unseptbium unsepttrium unseptquadium unseptpentium'
_=_ 'unsepthexium unseptseptium unseptoctium unseptennium unoctnilium unoctunium'
_=_ 'unoctbium unocttrium unoctquadium unoctpentium unocthexium unoctseptium unoctoctium'
_=_ 'unoctennium unennilium unennunium unennbium unenntrium unennquadium unennpentium'
_=_ 'unennhexium unennseptium unennoctium unennennium binilnilium'

haystack= _                                      /*assign the elements ───►  haystack.  */
needle  = 'gold'                                 /*we'll be looking for the gold.       */
upper needle haystack                            /*in case some people capitalize stuff.*/
idx= wordpos(needle, haystack)                   /*use REXX's BIF:  WORDPOS             */
if idx\==0  then return idx                      /*return the haystack  index  number.  */
else say  needle  "wasn't found in the haystack!"
return 0                                         /*indicates the needle  wasn't  found. */
/*stick a fork in it,  we're all done. */

## Ring

haystack = ["alpha","bravo","charlie","delta","echo","foxtrot","golf",
"hotel","india","juliet","kilo","lima","mike","needle",
"november","oscar","papa","quebec","romeo","sierra","tango",
"needle","uniform","victor","whisky","x-ray","yankee","zulu"]

needle = "needle"
maxindex = len(haystack)

for index = 1 to maxindex
if needle = haystack[index] exit ok
next
if index <= maxindex
see "first found at index " + index + nl ok
for last = maxindex to 0 step -1
if needle = haystack[last] exit ok
next
if !=index see " last found at index " + last + nl
else see "not found" + nl ok

Output:

first found at index : 14
last found at index : 22


## RPL

Works with: HP version 48G
{ "Zig" "Zag" "Zig" "Wally" "Ronald" "Bush" "Krusty" "Charlie" "Bush" "Bozo" } 'HAYSTACK' STO

≪ → up
≪ HAYSTACK
IF up NOT THEN REVLIST END
IF SWAP POS THEN
LASTARG
ELSE
"LOOKHAY Error:
END
≫ ≫ 'LOOKHAY' STO

"Bush" 1 LOOKHAY
"Bush" 0 LOOKHAY

Output:
2: 6
1: 2


## Ruby

haystack = %w(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo)

%w(Bush Washington).each do |needle|
if (i = haystack.index(needle))
puts "#{i} #{needle}"
else
raise "#{needle} is not in haystack\n"
end
end
Output:
4 Bush
search_a_list.rb:8:in block in <main>': Washington is not in haystack (RuntimeError)
from search_a_list.rb:4:in each'
from search_a_list.rb:4:in <main>'


Extra credit

haystack.each do |item|
last = haystack.rindex(item)
if last > haystack.index(item)
puts "#{item} last appears at index #{last}"
break
end
end
#=> Bush last appears at index 7

or

multi_item = haystack.each_index.group_by{|idx| haystack[idx]}.select{|key, val| val.length > 1}
# multi_item is => {"Bush"=>[4, 7]}
multi_item.each do |key, val|
puts "#{key} appears at index #{val}"
end
#=> Bush appears at index [4, 7]

## Rust

Rust encourages to encode possible errors in function's return type. For example, position returns Option<usize>, which can be None or Some(x).

fn main() {
let haystack=vec!["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie",
"Bush", "Boz", "Zag"];

println!("First occurence of 'Bush' at {:?}",haystack.iter().position(|s| *s=="Bush"));
println!("Last occurence of 'Bush' at {:?}",haystack.iter().rposition(|s| *s=="Bush"));
println!("First occurence of 'Rob' at {:?}",haystack.iter().position(|s| *s=="Rob"));
}
Output:
First occurence of 'Bush' at Some(4)
Last occurence of 'Bush' at Some(7)
First occurence of 'Rob' at None


### Version that panics

fn main() {
let haystack=vec!["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie",
"Bush", "Boz", "Zag"];

println!("First occurence of 'Bush' at {:?}",haystack.iter().position(|s| *s=="Bush").unwrap());
println!("Last occurence of 'Bush' at {:?}",haystack.iter().rposition(|s| *s=="Bush").unwrap());
println!("First occurence of 'Rob' at {:?}",haystack.iter().position(|s| *s=="Rob").unwrap());
}
Output:
First occurence of 'Bush' at 4
Last occurence of 'Bush' at 7
thread '<main>' panicked at 'called Option::unwrap() on a None value', /home/rustbuild/src/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libcore/option.rs:362
playpen: application terminated with error code 101


## S-lang

variable haystack = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo","Ronald"];

define find(needle)
{
variable i = where(haystack == needle);
if (length(i)) {
% print(sprintf("%s: first=%d, last=%d", needle, i[0], i[-1]));
return(i[0], i[-1]);
}
else
throw ApplicationError, "an exception";
}

($1,$2) = find("Ronald");     % returns 3, 9
($1,$2) = find("McDonald");   % throws ApplicationError, labelled "an exception"

## Sather

Translation of: C_sharp
class MAIN is
main is
haystack :ARRAY{STR} := |"Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo"|;
needles :ARRAY{STR} := | "Washington", "Bush" |;
loop needle ::= needles.elt!;
index ::= haystack.index_of(needle);
if index < 0 then
#OUT + needle + " is not in the haystack\n";
else
#OUT + index + " " + needle + "\n";
end;
end;
end;
end;

## Scala

The method indexOf, defined for all classes inheriting from, or having an implicit conversion to, Seq returns the index of the first element, or -1 if none exists. The method lastIndexOf does the same for the last element. Neither throws an exception, but that's easily done afterwards.

However, a simple implementation, not using those or similar methods might be written like this:

def findNeedles(needle: String, haystack: Seq[String]) = haystack.zipWithIndex.filter(_._1 == needle).map(_._2)
def firstNeedle(needle: String, haystack: Seq[String]) = findNeedles(needle, haystack).head
def lastNeedle(needle: String, haystack: Seq[String]) = findNeedles(needle, haystack).last

It does raise an exception if there's no needle.

## Scheme

(define haystack
'("Zig" "Zag" "Wally" "Ronald" "Bush" "Krusty" "Charlie" "Bush" "Bozo"))

(define index-of
(lambda (needle hackstack)
(let ((tail (member needle haystack)))
(if tail
(- (length haystack) (length tail))
(throw 'needle-missing)))))

(define last-index-of
(lambda (needle hackstack)
(let ((tail (member needle (reverse haystack))))
(if tail
(- (length tail) 1)
(throw 'needle-missing)))))
Output:
(index-of "Bush" haystack)
4
(last-index-of "Bush" haystack)
7


## SenseTalk

put ("apple", "banana", "cranberry" ,"durian", "eggplant", "grape", "banana", "appl", "blackberry") into fruitList

put findInList(fruitList,"banana")  // 2
put findInList(fruitList,"banana", true)  // 7
put findInList(fruitList,"tomato")  // throws an exception

function findInList paramList, paramItem, findLast
set temp to every offset of paramItem within paramList
if (number of items in temp = 0)
end if
if findLast
return last item of temp
else
return first item of temp
end if
end findInList

Note: Sensetalk indexes from 1

## Sidef

var haystack = %w(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo);

%w(Bush Washington).each { |needle|
var i = haystack.first_index{|item| item == needle};
if (i >= 0) {
say "#{i} #{needle}";
} else {
die "#{needle} is not in haystack";
}
}
Output:
4 Bush
Washington is not in haystack at find.sf line 9.


Extra credit:

var haystack = %w(Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo);
say haystack.last_index{|item| item == "Bush"};
Output:
7


define: #haystack -> ('Zig,Zag,Wally,Ronald,Bush,Krusty,Charlie,Bush,Bozo' splitWith: $,). {'Washington'. 'Bush'} do: [| :needle | (haystack indexOf: needle) ifNil: [inform: word ; ' is not in the haystack'] ifNotNilDo: [| :firstIndex lastIndex | inform: word ; ' is in the haystack at index ' ; firstIndex printString. lastIndex: (haystack lastIndexOf: word). lastIndex isNotNil /\ (lastIndex > firstIndex) ifTrue: [inform: 'last occurrence of ' ; word ; ' is at index ' ; lastIndex]]]. ## Smalltalk Works with: GNU Smalltalk Works with: Smalltalk/X Notice: Smalltalk indexes start at 1. | haystack | haystack := 'Zig,Zag,Wally,Ronald,Bush,Krusty,Charlie,Bush,Bozo' subStrings:$,.
{ 'Washington' . 'Bush' } do: [:word |
|t|

((t := haystack indexOf: word) = 0)
ifTrue: [ ('%1 is not in the haystack' % { word }) displayNl ]
ifFalse: [
|l|
('%1 is at index %2' % { word . t }) displayNl.
l := ( (haystack size) - (haystack reverse indexOf: word) + 1 ).
( t = l ) ifFalse: [
('last occurence of %1 is at index %2' %  { word . l }) displayNl ]
]
].

the above example did not raise an exception; the following does (a handler has been added to proceed for more search words):

Works with: Smalltalk/X

Notice: the code below uses the ST/X embedded-expression-string extension.

| haystack |
haystack := 'Zig,Zag,Wally,Ronald,Bush,Krusty,Charlie,Bush,Bozo' subStrings: $,. [ { 'Washington' . 'Bush' . 'Ronald' } do: [:word | |firstIdx lastIdx| firstIdx := haystack indexOf:word ifAbsent:[ ProceedableError raiseRequestWith:word errorString:'not found'. 0 ]. firstIdx = 0 ifFalse:[ (lastIdx := haystack lastIndexOf:word) = firstIdx ifTrue:[ e'the first index of {word} is {firstIdx}' printCR ] ifFalse:[ e'the last index of {word} is {lastIdx}' printCR ]] ] ] on:Error do:[:ex | e'{ex description} exception raised for: {ex parameter}' printCR. 'but I don''t care and proceed...' printCR. ex proceed. ] Output: not found exception raised for: Washington but I don't care and proceed... the last index of Bush is 8 the first index of Ronald is 4 ## Standard ML fun find_index (pred, lst) = let fun loop (n, []) = NONE | loop (n, x::xs) = if pred x then SOME n else loop (n+1, xs) in loop (0, lst) end; val haystack = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"]; app (fn needle => case find_index (fn x => x = needle, haystack) of SOME i => print (Int.toString i ^ " " ^ needle ^ "\n") | NONE => print (needle ^ " is not in haystack\n")) ["Washington", "Bush"]; ## Swift Works with: Swift version 2.x+ let haystack = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"] for needle in ["Washington","Bush"] { if let index = haystack.indexOf(needle) { print("\(index) \(needle)") } else { print("\(needle) is not in haystack") } } Works with: Swift version 1.x let haystack = ["Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"] for needle in ["Washington","Bush"] { if let index = find(haystack, needle) { println("\(index) \(needle)") } else { println("\(needle) is not in haystack") } } The second task: Works with: Swift version 2.x+ // the second part can be done several ways, but extending any Array of Comparable objects is the most generic approach extension Array where Element : Comparable { func lastIndexMatching(needle:Element) -> Int? { for i in stride(from: count-1, through: 0, by: -1) { if self[i] == needle { return i } } return nil } } for needle in ["Washington","Bush"] { if let index = haystack.lastIndexMatching(needle) { print("\(index) \(needle)") } else { print("\(needle) is not in haystack") } } ## Tcl set haystack {Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo} foreach needle {Bush Washington} { if {[set idx [lsearch -exact$haystack $needle]] == -1} { error "$needle does not appear in the haystack"
} else {
puts "$needle appears at index$idx in the haystack"
}
}

Extra credit:

set haystack {Zig Zag Wally Ronald Bush Krusty Charlie Bush Bozo}
foreach needle {Bush Washington} {
set indices [lsearch -all -exact $haystack$needle]
if {[llength $indices] == 0} { error "$needle does not appear in the haystack"
} else {
puts "$needle appears first at index [lindex$indices 0] and last at [lindex $indices end]" } } ## TorqueScript --Elm 03:38, 18 June 2012 (UTC) Find multiple needles in a haystack: function findIn(%haystack,%needles) { %hc = getWordCount(%haystack); %nc = getWordCount(%needles); for(%i=0;%i<%nc;%i++) { %nword = getWord(%needles,%i); %index[%nword] = -1; } for(%i=0;%i<%hc;%i++) { %hword = getWord(%haystack,%i); for(%j=0;%j<%nc;%j++) { %nword = getWord(%needles,%j); if(%hword$= %nword)
{
%index[%nword] = %i;
}
}
}

for(%i=0;%i<%nc;%i++)
{
%nword = getWord(%needles,%i);
%string = %string SPC %nword@"_"@%index[%nword];
%string = trim(%string);
}

return %string;
}

How to use it:

echo(findIn("Hello world, you are quite sunny today.","quite hello somethingelse"));

returns:

=> "quite_4 hello_0 somethingelse_-1"

## TUSCRIPT

 MODE TUSCRIPT
SET haystack="Zig'Zag'Wally'Ronald'Bush'Krusty'Charlie'Bush'Bozo"
PRINT "haystack=",haystack
LOOP needle="Washington'Bush'Wally"
SET table  =QUOTES (needle)
BUILD S_TABLE needle = table
IF (haystack.ct.needle) THEN
BUILD R_TABLE needle = table
SET position=FILTER_INDEX(haystack,needle,-)
RELEASE R_TABLE needle
PRINT "haystack contains ", needle, " on position(s): ",position
ELSE
PRINT "haystack not contains ",needle
ENDIF
RELEASE S_TABLE needle
ENDLOOP
Output:
haystack=Zig'Zag'Wally'Ronald'Bush'Krusty'Charlie'Bush'Bozo
haystack not contains Washington
haystack contains Bush on position(s): 5'8
haystack contains Wally on position(s): 3


## UNIX Shell

Works with: Almquist Shell
Works with: bash
Works with: ksh93
Works with: pdksh
Works with: Z Shell
if [ $1 ];then haystack="Zip Zag Wally Ronald Bush Krusty Charlie Bush Bozo" index=$(echo $haystack|tr " " "\n"|grep -in "^$1$") if [$? = 0 ];then
quantity_of_hits=$(echo$index|tr " " "\n"|wc -l|tr -d " ")
first_index=$(echo$index|cut -f 1 -d ":")
if [ $quantity_of_hits = 1 ];then echo The sole index for$1 is: $first_index else echo The smallest index for$1 is: $first_index greatest_index=$(echo $index|tr " " "\n"|tail -1|cut -f 1 -d ":") echo "The greatest index for$1 is: $greatest_index";fi else echo$1 is absent from haystatck.;fi
else echo Must provide string to find in haystack.;fi
Output:
./needle_haystack clay     ---> clay is absent from haystatck.
./needle_haystack charlie  ---> The sole index for charlie is: 7
./needle_haystack bush     ---> The smallest index for bush is: 5
The greatest index for bush is: 8

## Ursala

The indices function takes a pair ${\displaystyle (needle,haystack)}$ of any type, treats haystack as a list, and returns the pair of indices giving the first and last positions of needle in it, which are numbered from zero and may be equal. If it's not present, an exception is thrown with a diagnostic message of 'missing'. The search is expressed by ~|, the built-in distributing filter operator.

#import std

indices = ||<'missing'>!% ~&nSihzXB+ ~&lrmPE~|^|/~& num

The explanation is somewhat longer than the program.

• The ^| operator takes a right operand consisting of a pair of functions ${\displaystyle (f,g)}$, and returns a function that takes a pair ${\displaystyle (x,y)}$ to the result ${\displaystyle (f(x),g(y))}$.
• An expression of the form h/f g where h is a function taking a pair, is equivalent to h(f,g).
• The ~& operator represents the identity function.
• The expression ^|/~& num applied to an argument ${\displaystyle (needle,haystack)}$ therefore evaluates to ${\displaystyle (needle,}$num ${\displaystyle haystack)}$
• The num function takes any list ${\displaystyle \langle x_{0},x_{1}\dots x_{n}\rangle }$ and transforms it to a list of pairs ${\displaystyle \langle (0,x_{0}),(1,x_{1})\dots (n,x_{n})\rangle }$.
• The left operand to the ^| operator, if any, is composed with the function constructed from the right. In this case, the left operand is ~&lrmPE~|
• The ~| operator takes a predicate as its left operand and returns a function that operates on a pair ${\displaystyle (a,b)}$, where ${\displaystyle b}$ is expected to be a list. The resulting function is evaluated by pairing ${\displaystyle a}$ with each item of ${\displaystyle b}$, applying the predicate to each pair, and making a list of the items of ${\displaystyle b}$ for which the predicate holds on the pair.
• The predicate in this case is ~&lrmPE, which will be passed an input of the form ${\displaystyle (needle,(i,x_{i}))}$ for the ${\displaystyle i}$-th item in terms of the notation above.
• The expression ~&lrmPE has a root operator E, which tests for equality, a left operand l, which extracts the left side of its argument, and a right operand of rmP, which is the reverse composition (P) of the right side extraction (r) operator, followed by a further right side extraction expressed more idiomatically as m when the argument in question represents some type of key-value pair.
• The predicate therefore compares the left side of ${\displaystyle (needle,(i,x_{i}))}$, which is ${\displaystyle needle}$, to the right of the right, which is ${\displaystyle x_{i}}$
• The result from ~&lrmPE~| will be a list of pairs of the form ${\displaystyle (i,needle)}$, for indices ${\displaystyle i}$ at which ${\displaystyle needle}$ appears in the list.
• This result is passed to the function ~&nSihzXB, which consists of subexpressions nS and ihzXB that operate sequentially.
• The nS subexpression makes a list of the left sides of all items of a list of key-value pairs, in this case constructing a list of indices ${\displaystyle i}$ from the input, and passing it to the subexpression ihzXB.
• The subexpression ihzXB has a left subexpression i, a right subexpression hzX and a root B.
• The B (mnemonic for "both") operator causes the left subexpression to be applied to the argument as a test, and if the result is non-empty, returns the result of applying the right.
• The left subexpression i represents the identity function, and tests whether the argument list is non-empty.
• If the list is non-empty, the expression hzX constructs the pair (X) of the head (h) and the last item (z) of the list given in the argument.
• The disjunction operator || used in an expression of the form ||u v with functions u and v constructs a function that applies v to the argument, returns that result if non-empty, but otherwise returns the the result of applying v to the argument.
• The expression <'missing'> is a list of strings representing the diagnostic message to be returned in the event of an empty list (corresponding to the ${\displaystyle needle}$ not being present).
• The constant operator (!) is used because the message is not data-dependent.
• The exception throwing operator (%) compels the result of its operand to be returned in a way that bypasses the usual flow of control.

Test program:

#cast %nW

test = indices/'bar' <'foo','bar','baz','bar'>
Output:
(1,3)

## VBA

Function IsInArray(stringToBeFound As Variant, arr As Variant, _
Optional start As Integer = 1, Optional reverse As Boolean = False) As Long
Dim i As Long, lo As Long, hi As Long, stp As Long
IsInArray = -1
If reverse Then
lo = UBound(arr): hi = start: stp = -1
Else
lo = start: hi = UBound(arr): stp = 1
End If
For i = lo To hi Step stp 'start in stead of LBound(arr)
If StrComp(stringToBeFound, arr(i), vbTextCompare) = 0 Then
IsInArray = i
Exit For
End If
Next i
End Function
Public Sub search_a_list()
Dim haystack() As Variant, needles() As Variant
haystack = [{"Zig","Zag","Wally","Ronald","Bush","Krusty","Charlie","Bush","Bozo"}]
needles = [{"Washington","Bush"}]
For i = 1 To 2
If IsInArray(needles(i), haystack) = -1 Then
Else
Debug.Print needles(i); " is at position "; CStr(IsInArray(needles(i), haystack)); ".";
Debug.Print " And last position is ";
Debug.Print CStr(IsInArray(needles(i), haystack, 1, True)); "."
End If
Next i
End Sub
Output:
Washington not found in haystack.
Bush is at position 5. And last position is 8.

## VBScript

Shamelessly derived from the BASIC version.

data = "foo,bar,baz,quux,quuux,quuuux,bazola,ztesch,foo,bar,thud,grunt," &_
"foo,bar,bletch,foo,bar,fum,fred,jim,sheila,barney,flarp,zxc," &_
"spqr,wombat,shme,foo,bar,baz,bongo,spam,eggs,snork,foo,bar," &_
"zot,blarg,wibble,toto,titi,tata,tutu,pippo,pluto,paperino,aap," &_
"noot,mies,oogle,foogle,boogle,zork,gork,bork"

haystack = Split(data,",")

Do
WScript.StdOut.Write "Word to search for? (Leave blank to exit) "
If needle <> "" Then
found = 0
For i = 0 To UBound(haystack)
If UCase(haystack(i)) = UCase(needle) Then
found = 1
WScript.StdOut.Write "Found " & Chr(34) & needle & Chr(34) & " at index " & i
WScript.StdOut.WriteLine
End If
Next
If found < 1 Then
WScript.StdOut.WriteLine
End If
Else
Exit do
End If
Loop
Output:
F:\VBScript>cscript /nologo search_a_list.vbs
Word to search for? (Leave blank to exit) foo
Found "foo" at index 0
Found "foo" at index 8
Found "foo" at index 12
Found "foo" at index 15
Found "foo" at index 27
Found "foo" at index 34
Word to search for? (Leave blank to exit) bar
Found "bar" at index 1
Found "bar" at index 9
Found "bar" at index 13
Found "bar" at index 16
Found "bar" at index 28
Found "bar" at index 35
Word to search for? (Leave blank to exit) fff
Word to search for? (Leave blank to exit)

F:\VBScript>

## V (Vlang)

const (
haystacks = ["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo"]
needles = ["Bush", "washington", "Wally"]
)

fn main() {
mut list, mut index, mut count, mut missing := "", "", "", ""
for nee in needles {
for idx, hay in haystacks {
if nee == hay {
count = "${haystacks.str().count(nee)}" if list.contains(nee) { index += ",${idx}"
list = "Found: ${nee}; Index:${index}; Count: ${count}\n" } else { index = "${idx}"
list += "Found: ${nee}; Index:${index}; Count: ${count}\n" } } } if nee !in haystacks && !missing.contains(nee) {missing += "Missing:${nee}\n"}
}
list += missing
println(list.all_before_last('\n'))
}
Output:
Found: Bush; Index: 4, 7; Count: 2
Found: Wally; Index: 2; Count: 1
Missing: washington


## Wart

Wart uses the function pos to search a list for an element. Here's how it's implemented:

def (pos x (seq | (head ... tail)) n)
default n :to 0
if seq
n
(pos x tail n+1)
Usage:
pos 3 '(1 2 3 4 5)
=> 2
pos 24 '(1 2 3 4 5)
=> nil

## Wren

Library: Wren-seq
import "./seq" for Lst

var find = Fn.new { |haystack, needle|
var res = Lst.indicesOf(haystack, needle)
System.print("The needle occurs %(res[1]) time(s) in the haystack.")
if (res[1] == 1) {
System.print("It occurs at index %(res[2][0])")
} else {
System.print("It first occurs at index %(res[2][0])")
System.print("It last  occurs at index %(res[2][-1])")
}
System.print()
}

var haystack = ["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"]
System.print("The haystack is:\n%(haystack)\n")
var needles = ["Wally", "Bush", "Zag", "George"]
for (needle in needles) {
System.print("The needle is %(needle).")
find.call(haystack, needle)
}
Output:
The haystack is:
[Zig, Zag, Wally, Ronald, Bush, Krusty, Charlie, Bush, Boz, Zag]

The needle is Wally.
The needle occurs 1 time(s) in the haystack.
It occurs at index 2

The needle is Bush.
The needle occurs 2 time(s) in the haystack.
It first occurs at index 4
It last  occurs at index 7

The needle is Zag.
The needle occurs 2 time(s) in the haystack.
It first occurs at index 1
It last  occurs at index 9

The needle is George.
[./search_list line 5] in new(_) block argument
[./search_list line 21] in (script)


## XPL0

\Based on C example:
include c:\cxpl\stdlib;     \provides StrCmp routine, etc.
int Haystack;               \('int' is used instead of 'char' for 2D array)

func Search(Str, First);    \Return first (or last) index for string in haystack
char Str; int First;
int I, SI;
[I:= 0;  SI:= 0;
repeat  if StrCmp(Str, Haystack(I)) = 0 then
[if First then return I;
SI:= I;     \save index
];
I:= I+1;
until   Haystack(I) = 0;
return SI;
];

[Haystack:= ["Zig", "Zag", "Wally", "Ronald", "Bush",
"Krusty", "Charlie", "Bush", "Boz", "Zag", 0];
Text(0, "Bush is at ");  IntOut(0, Search("Bush", true));  CrLf(0);
if Search("Washington", true) = 0 then
Text(0, "Washington is not in the haystack^M^J");
Text(0, "First index for Zag: ");  IntOut(0, Search("Zag", true));  CrLf(0);
Text(0,  "Last index for Zag: ");  IntOut(0, Search("Zag", false)); CrLf(0);
]
Output:
Bush is at 4
Washington is not in the haystack
First index for Zag: 1
Last index for Zag: 9


## Yorick

haystack = ["Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Bozo"];
needles = ["Bush", "Washington"];
for(i = 1; i <= numberof(needles); i++) {
w = where(haystack == needles(i));
if(!numberof(w))
write, format="Needle %s appears first at index %d\n", needles(i), w(1);
if(numberof(w) > 1)
write, format="Needle %s appears last at index %d\n", needles(i), w(0);
}

## zkl

L("Krusty","Charlie","Bozo","Bozo").index("Charlie") //--> 1
L("Krusty","Charlie","Bozo","Bozo").index("fred") //--> throws index error

Find last needle:

haystack:=L("Krusty","Charlie","Bozo","Bozo");
haystack.len() - 1 - haystack.reverse().index("Bozo");  // or this
haystack:=Data(0,String,"Krusty","Charlie","Bozo","Bozo");
//-->7`