Loops/Continue: Difference between revisions
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C5001 FORMAT (I3, ',', ADVANCE='NO') |
C5001 FORMAT (I3, ',', ADVANCE='NO') |
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END</lang> |
END</lang> |
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=={{header|GAP}}== |
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<lang gap>for i in [1 .. 11] do |
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if RemInt(i, 5) = 0 then |
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Print(i, "\n"); |
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continue; |
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fi; |
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Print(i, ", "); |
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od; |
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# 1, 2, 3, 4, 5 |
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# 6, 7, 8, 9, 10</lang> |
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=={{header|GML}}== |
=={{header|GML}}== |
Revision as of 19:55, 8 June 2011
You are encouraged to solve this task according to the task description, using any language you may know.
Show the following output using one loop.
1, 2, 3, 4, 5 6, 7, 8, 9, 10
Try to achieve the result by forcing the next iteration within the loop upon a specific condition, if your language allows it.
Ada
Ada has no continue reserved word, nor does it need one. The continue reserved word is only syntactic sugar for operations that can be achieved without it as in the following example.
<lang ada>with Ada.Text_Io; use Ada.Text_Io;
procedure Loop_Continue is begin
for I in 1..10 loop Put(Integer'Image(I)); if I mod 5 = 0 then New_Line; else Put(","); end if; end loop;
end Loop_Continue;</lang>
Aikido
<lang aikido>foreach i 1..10 {
print (i) if ((i % 5) == 0) { println() continue } print (", ")
}</lang>
ALGOL 68
ALGOL 68 has no continue reserved word, nor does it need one. The continue reserved word is only syntactic sugar for operations that can be achieved without it as in the following example: <lang algol68>FOR i FROM 1 TO 10 DO
print ((i, IF i MOD 5 = 0 THEN new line ELSE "," FI ))
OD</lang> Output:
+1, +2, +3, +4, +5 +6, +7, +8, +9, +10
AutoHotkey
<lang autohotkey>Loop, 10 {
Delimiter := (A_Index = 5) || (A_Index = 10) ? "`n":", " Index .= A_Index . Delimiter
} MsgBox %Index%</lang>
AWK
<lang awk>BEGIN {
for(i=1; i <= 10; i++) { printf("%d", i) if ( i % 5 == 0 ) { print continue } printf(", ") }
}</lang>
bc
Requires a bc with the print and continue statements. POSIX bc has not these statements.
<lang bc>for (i = 1; i <= 10; i++) { print i if (i % 5) { print ", " continue } print "\n" } quit</lang>
C
<lang c>for(int i = 1;i <= 10; i++){
printf("%d", i); if(i % 5 == 0){ printf("\n"); continue; } printf(", ");
}</lang>
C++
<lang cpp>for(int i = 1;i <= 10; i++){
cout << i; if(i % 5 == 0){ cout << endl; continue; } cout << ", ";
}</lang>
C#
<lang csharp>using System;
class Program {
static void Main(string[] args) { for (int i = 1; i <= 10; i++) { Console.Write(i);
if (i % 5 == 0) { Console.WriteLine(); continue; }
Console.Write(", "); } }
}</lang>
Clojure
Clojure doesn't have a continue keyword. It has a recur keyword, although I prefer to work with ranges in this case. <lang clojure>(doseq
[n (range 1 11)] (do (print n) (if (= (rem n 5) 0) (print "\n") (print ", "))))</lang>
ColdFusion
Remove the leading space from the line break tag. <lang cfm><cfscript>
for( i = 1; i <= 10; i++ ) { writeOutput( i ); if( 0 == i % 5 ) { writeOutput( "< br />" ); continue; } writeOutput( "," ); }
</cfscript></lang>
Common Lisp
Common Lisp doesn't have a continue keyword, but the do
iteration construct does use an implicit tagbody
, so it's easy to go
to any label. Four solutions follow. The first pushes the conditional (whether to print a comma and a space or a newline) into the format string. The second uses the implicit tagbody
and go
. The third is a do loop with conditionals outside of the output functions.
<lang lisp>(do ((i 1 (1+ i))) ((> i 10))
(format t "~a~:[, ~;~%~]" i (zerop (mod i 5))))
(do ((i 1 (1+ i))) ((> i 10))
(write i) (when (zerop (mod i 5)) (terpri) (go end)) (write-string ", ") end)
(do ((i 1 (1+ i))) ((> i 10))
(write i) (if (zerop (mod i 5)) (terpri) (write-string ", ")))</lang>
These use the loop
iteration form, which does not contain an implicit tagbody (though one could be explicitly included). The first uses an explicit condition to omit the rest of the loop; the second uses block
/return-from
to obtain the effect of skipping the rest of the code in the block
which makes up the entire loop body.
<lang lisp>(loop for i from 1 to 10
do (write i) if (zerop (mod i 5)) do (terpri) else do (write-string ", "))
(loop for i from 1 to 10 do
(block continue (write i) (when (zerop (mod i 5)) (terpri) (return-from continue)) (write-string ", ")))</lang>
D
<lang d>for(int i = 1;i <= 10; i++){
writef(i); if(i % 5 == 0){ writefln(); continue; } writef(", ");
}</lang>
dc
The four commands # n J M are special to OpenBSD dc. The # command starts a comment. The n command prints a number without a newline.
<lang dc>1 si # i = 1 [2Q]sA # A = code to break loop [[, ]P 1J]sB # B = code to print comma, continue loop [
li n # print i li 5 % 0 !=B # call B if i % 5 [
]P # print newline
M # mark from calling B li 1 + si # i += 1 li 10!<C # continue loop if 10 >= i
]sC li 10!<C # enter loop if 10 >= i</lang>
This program uses J and M to force the next iteration of a loop. The nJ command breaks n levels of brackets (like nQ does so), but then skips to the next M command. One can place M at the end of the iteration.
Delphi
<lang Delphi> var
i:Integer;
begin
for i := 1 to 10 do begin Write(i); if i mod 5 = 0 then begin Writeln(); continue; end; Write(','); end;
end.
</lang>
Ela
Direct Approach
<lang ela>open Con
let loop n | n > 10 = ()
| else = rec write n f $ loop (n+1) where f | n % 5 == 0 = "\r\n" | else = ", "
loop 1</lang>
Function rec creates a cyclic version of a given function, it is defined in standard Prelude as 'let rec f x = f x $ rec f' where '$' is a sequencing operator.
Using list
<lang ela>open Con
let loop [] = ()
loop (x::xs) = rec write x c $ loop xs where c | x % 5 == 0 = "\r\n" | else = ", "
loop [1..10]</lang>
This version is more generic and can work for any given range of values.
Factor
There is no built-in continue
in Factor.
<lang factor>1 10 [a,b] [
[ number>string write ] [ 5 mod 0 = "\n" ", " ? write ] bi
] each</lang>
Fantom
While and for loops support continue
to jump back to begin the next iteration of the loop.
<lang fantom> class LoopsContinue {
public static Void main () { for (Int i := 1; i <= 10; ++i) { Env.cur.out.print (i) if (i % 5 == 0) { Env.cur.out.printLine ("") continue } Env.cur.out.print (", ") } Env.cur.out.printLine ("") }
} </lang>
Forth
Although this code solves the task, there is no portable equivalent to "continue" for either DO-LOOPs or BEGIN loops. <lang forth>: main
11 1 do i dup 1 r. 5 mod 0= if cr else [char] , emit space then loop ;</lang>
Fortran
<lang fortran>do i = 1, 10
write(*, '(I0)', advance='no') i if ( mod(i, 5) == 0 ) then write(*,*) cycle end if write(*, '(A)', advance='no') ', '
end do</lang>
<lang fortran>C WARNING: This program is not valid ANSI FORTRAN 77 code. It uses C one nonstandard character on the line labelled 5001. Many F77 C compilers should be okay with it, but it is *not* standard. C C It is also worth noting that FORTRAN 77 uses the command CONTINUE, C but not in the semantic, looping sense of the word. In FORTRAN, C CONTINUE means "do absolutely nothing." It is a placeholder. If C anything, it means "continue to the next line." C C Python does the same thing with `pass`; C and its family of C languages, with `{/* do nothing */}`. Write CONTINUE when you need C to write something but have nothing to write. C C This page on Rosetta Code is about a very different "continue" C statement that tells a loop to go back to the beginning. In C FORTRAN, we use (you guessed it!) a GOTO to accomplish this.
PROGRAM CONTINUELOOP INTEGER I
DO 10 I = 1, 10
C Is it five or ten?
IF (MOD(I, 5) .EQ. 0) THEN
C If it is, write a newline and no comma.
WRITE (*,5000) I
C Continue the loop; that is, skip to the end of the loop.
GOTO 10 ENDIF
C Write I with a comma and no newline.
WRITE (*,5001) I
C Again, in this case, CONTINUE is completely unrelated to the C semantic, looping sense of the word.
10 CONTINUE
STOP
C This will print an integer and a newline (no comma).
5000 FORMAT (I3)
C Standard FORTRAN 77 is completely incapable of completing a C WRITE statement without printing a newline. If you want to print C five integers in standard code, you have to do something like C this: C C FORMAT (I3, ',', I3, ',', I3, ',', I3, ',', I3) C C Writing `1, 2, 3, 4, 5` and then `6, 7, 8, 9, 10` to that format C would produce the following two lines: C C 1, 2, 3, 4, 5 C 6, 7, 8, 9, 10 C C However, this code exists to demonstrate continuing a FORTRAN 77 C loop and not to demonstrate how to get around its rigidity about C newlines. C C The dollar sign at the end of the format is a nonstandard C character. It tells the compiler not to print a newline. If you C are actually using FORTRAN 77, you should figure out what your C particular compiler accepts. If you are actually using Fortran C 90 or later, you should replace this line with the commented C line that follows it.
5001 FORMAT (I3, ',', $)
C5001 FORMAT (I3, ',', ADVANCE='NO')
END</lang>
GAP
<lang gap>for i in [1 .. 11] do
if RemInt(i, 5) = 0 then Print(i, "\n"); continue; fi; Print(i, ", ");
od;
- 1, 2, 3, 4, 5
- 6, 7, 8, 9, 10</lang>
GML
<lang GML>for(i = 1; i <= 10; i += 1)
{ show_message(string(i)) i += 1 if(i <= 10) continue }</lang>
Go
<lang go>for i := 1; i <= 10; i++ {
fmt.Printf("%d", i) if i % 5 == 0 { fmt.Printf("\n") continue } fmt.Printf(", ")
}</lang>
Groovy
<lang groovy>for (i in 1..10) {
print i if (i % 5 == 0) { println () continue } print ', '
}</lang>
Haskell
As a functional language, it is not idiomatic to have true loops - recursion is used instead. Below is one of many possible implementations of the task. The below code uses a guard (| symbol) to compose functions differently for the two alternative output paths, instead of using continue like in an imperative language.
<lang haskell>import Control.Monad (forM) main = forM [1..10] out
where out x | (x `mod` 5 == 0) = (putStrLn . show) x | otherwise = (putStr . (++", ") . show) x</lang>
HicEst
<lang hicest>DO i = 1, 10
IF( MOD(i, 5) == 1 ) THEN WRITE(Format="i3") i ELSE WRITE(APPend, Format=" ',', i3 ") i ENDIF
ENDDO </lang>
Icon and Unicon
The following code demonstrates the use of 'next' (the reserved word for 'continue'): <lang Icon>procedure main() every writes(x := 1 to 10) do {
if x % 5 = 0 then { write() next } writes(", ") }
end</lang> However, the output sequence can be written without 'next' and far more succinctly as: <lang Icon>every writes(x := 1 to 10, if x % 5 = 0 then "\n" else ", ")</lang>
J
J is array-oriented, so there is very little need for loops. For example, one could satisfy this task this way:
<lang j>_2}."1'lq<, >'8!:2>:i.2 5</lang>
J does support loops for those times they can't be avoided (just like many languages support gotos for those time they can't be avoided). <lang j>3 : 0 ] 10
z=. for_i. 1 + i.y do. z =. z , ": i
if. 0 = 5 | i do. z 1!:2 ]2 z =. continue. end.
z =. z , ', ' end. i.0 0 )</lang>
Though it's rare to see J code like this.
Java
<lang java>for(int i = 1;i <= 10; i++){
System.out.print(i); if(i % 5 == 0){ System.out.println(); continue; } System.out.print(", ");
}</lang>
JavaScript
Using the print()
function from Rhino or SpiderMonkey.
<lang javascript>var output = "";
for (var i = 1; i <= 10; i++) {
output += i; if (i % 5 == 0) { print(output); output = ""; continue; } output += ", ";
}</lang>
Lisaac
<lang Lisaac>1.to 10 do { i : INTEGER;
i.print; (i % 5 = 0).if { '\n'.print; } else { ','.print; };
};</lang>
Lua
<lang Lua>for i = 1, 10 do
io.write( i ) if i % 5 == 0 then io.write( "\n" ) else io.write( ", " ) end
end</lang>
Mathematica
<lang Mathematica>tmp = ""; For[i = 1, i <= 10, i++,
tmp = tmp <> ToString[i]; If[Mod[i, 5] == 0, tmp = tmp <> "\n"; , tmp = tmp <> ", "; ]; ];
Print[tmp]</lang>
MAXScript
<lang maxscript>for i in 1 to 10 do (
format "%" i if mod i 5 == 0 then ( format "\n" continue ) continue format ", "
)</lang>
Metafont
Metafont has no a continue (or similar) keyword. As the Ada solution, we can complete the task just with conditional.
<lang metafont>string s; s := ""; for i = 1 step 1 until 10: if i mod 5 = 0:
s := s & decimal i & char10;
else:
s := s & decimal i & ", "
fi; endfor message s; end</lang>
Since message append always a newline at the end, we need to build a string and output it at the end, instead of writing the output step by step.
Note: mod is not a built in; like TeX, "bare Metafont" is rather primitive, and normally a set of basic macros is preloaded to make it more usable; in particular mod is defined as
<lang metafont>primarydef x mod y = (x-y*floor(x/y)) enddef;</lang>
Modula-3
Modula-3 defines the keyword RETURN as an exception, but when it is used with no arguments it works just like continue in C.
Note, however, that RETURN only works inside a procedure or a function procedure; use EXIT otherwise.
Module code and imports are omitted. <lang modula3>FOR i := 1 TO 10 DO
IO.PutInt(i); IF i MOD 5 = 0 THEN IO.Put("\n"); RETURN; END; IO.Put(", ");
END;</lang>
MOO
<lang moo>s = ""; for i in [1..10]
s += tostr(i); if (i % 5 == 0) player:tell(s); s = ""; continue; endif s += ", ";
endfor</lang>
OCaml
There is no continue statement for for loops in OCaml, but it is possible to achieve the same effect with an exception. <lang ocaml># for i = 1 to 10 do
try print_int i; if (i mod 5) = 0 then raise Exit; print_string ", " with Exit -> print_newline() done ;;
1, 2, 3, 4, 5 6, 7, 8, 9, 10 - : unit = ()</lang> Though even if the continue statement does not exist, it is possible to add it with camlp4.
Octave
<lang octave>v = ""; for i = 1:10
v = sprintf("%s%d", v, i); if ( mod(i, 5) == 0 ) disp(v) v = ""; continue endif v = sprintf("%s, ", v);
endfor</lang>
Oz
By using the "continue" feature of the for-loop, we bind C to a nullary procedure which, when invoked, immediately goes on to the next iteration of the loop. <lang oz>for I in 1..10 continue:C do
{System.print I} if I mod 5 == 0 then {System.printInfo "\n"} {C} end {System.printInfo ", "}
end</lang>
PARI/GP
<lang parigp>for(n=1,10,
print1(n); if(n%5 == 0, print();continue); print1(", ")
)</lang>
Perl
<lang perl>foreach (1..10) {
print $_; if ($_ % 5 == 0) { print "\n"; next; } print ', ';
}</lang>
Perl 6
<lang perl6>for 1 .. 10 {
.print; if $_ %% 5 { print "\n"; next; } print ', ';
}</lang>
or without using a loop:
<lang perl6>$_.join(", ").say for [1..5], [6..10];</lang>
PHP
<lang php>for ($i = 1; $i <= 10; $i++) {
echo $i; if ($i % 5 == 0) { echo "\n"; continue; } echo ', ';
}</lang>
PicoLisp
PicoLisp doesn't have an explicit 'continue' functionality. It can always be emulated with a conditional expression. <lang PicoLisp>(for I 10
(print I) (if (=0 (% I 5)) (prinl) (prin ", ") ) )</lang>
Pike
<lang pike>int main(){
for(int i = 1; i <= 10; i++){ write(sprintf("%d",i)); if(i % 5 == 0){ write("\n"); continue; } write(", "); }
}</lang>
PL/I
<lang PL/I>loop: do i = 1 to 10;
put edit (i) (f(3)); if mod(i,5) = 0 then do; put skip; iterate loop; end; put edit (', ') (a);
end;</lang>
Pop11
<lang pop11>lvars i; for i from 1 to 10 do
printf(i, '%p'); if i rem 5 = 0 then printf('\n'); nextloop; endif; printf(', ')
endfor;</lang>
PowerShell
<lang powershell>for ($i = 1; $i -le 10; $i++) {
Write-Host -NoNewline $i if ($i % 5 -eq 0) { Write-Host continue } Write-Host -NoNewline ", "
}</lang>
PureBasic
<lang purebasic>OpenConsole()
For i.i = 1 To 10
Print(Str(i)) If i % 5 = 0 PrintN("") Continue EndIf Print(",")
Next
Repeat: Until Inkey() <> ""</lang>
Python
<lang python>for i in xrange(1,11):
if i % 5 == 0: print i continue print i, ",",</lang>
R
<lang R>for(i in 1:10) {
cat(i) if(i %% 5 == 0) { cat("\n") next } cat(", ")
}</lang>
REBOL
<lang REBOL>REBOL [ Title: "Loop/Continue" Author: oofoe Date: 2010-01-05 URL: http://rosettacode.org/wiki/Loop/Continue ]
- REBOL does not provide a 'continue' word for loop constructs,
- however, you may not even miss it
print "One liner (compare to ALGOL 68 solution):" repeat i 10 [prin rejoin [i either 0 = mod i 5 [crlf][", "]]]
print [crlf "Port of ADA solution:"] for i 1 10 1 [ prin i either 0 = mod i 5 [ prin newline ][ prin ", " ] ]</lang>
Output:
One liner (compare to ALGOL 68 solution): 1, 2, 3, 4, 5 6, 7, 8, 9, 10 Port of ADA solution: 1, 2, 3, 4, 5 6, 7, 8, 9, 10
REXX
(Remember that there exists implementations of the REXX language that needs that the source begins with /*, i.e. with a comment) <lang rexx>do i = 1 to 10
call charout ,i", " if i//5 = 0 then do say iterate end
end</lang>
Ruby
<lang ruby>for i in 1..10 do
print i if i % 5 == 0 then puts next end print ', '
end</lang> The "for" look could be written like this: <lang ruby>(1..10).each do |i| ... 1.upto(10) do |i| ... 10.times do |n| i=n+1; ...</lang> Without meeting the criteria (showing loop continuation), this task could be written as: <lang ruby>1.upto(10) {|i| print "%d%s" % [i, i%5==0 ? "\n" : ", "]}</lang>
Sather
There's no continue!
in Sather. The code solve the task without forcing a new iteration.
<lang sather>class MAIN is
main is i:INT; loop i := 1.upto!(10); #OUT + i; if i%5 = 0 then #OUT + "\n"; else #OUT + ", "; end; end; end;
end;</lang>
Scheme
<lang scheme>(define (loop i)
(if (> i 10) 'done (begin (display i) (cond ((zero? (modulo i 5)) (newline) (loop (+ 1 i))) (else (display ", ") (loop (+ 1 i)))))))</lang>
Suneido
<lang Suneido>ob = Object() for (i = 1; i <= 10; ++i)
{ ob.Add(i) if i is 5 { Print(ob.Join(',')) ob = Object() } }
Print(ob.Join(','))</lang>
Output: <lang Suneido>1,2,3,4,5 6,7,8,9,10 ok</lang>
Tcl
<lang tcl>for {set i 1} {$i <= 10} {incr i} {
puts -nonewline $i if {$i % 5 == 0} { puts "" continue } puts -nonewline ", "
}</lang>
TI-89 BASIC
<lang ti-89>count() Prgm
""→s For i,1,10 s&string(i)→s If mod(i,5)=0 Then Disp s ""→s Cycle EndIf s&", "→s EndFor
EndPrgm</lang>
Ti-89 lacks support for multi-argument display command or controlling the print position so that one can print several data on the same line. The display command (Disp) only accepts one argument and prints it on a single line (causing a line a feed at the end, so that the next Disp command will print in the next line). The solution is appending data to a string (s), using the concatenator operator (&), by converting numbers to strings, and then printing the string at the end of the line.
TUSCRIPT
<lang tuscript> $$ MODE TUSCRIPT numbers="" LOOP n=1,10 numbers=APPEND (numbers,", ",n) rest=n%5 IF (rest!=0) CYCLE
PRINT numbers numbers=""
ENDLOOP </lang> Output:
1, 2, 3, 4, 5 6, 7, 8, 9, 10
UnixPipes
<lang bash>yes \ | cat -n | head -n 10 | xargs -n 5 echo | tr ' ' ,</lang>
UNIX Shell
<lang bash>Z=1 while (( Z<=10 )); do
echo -e "$Z\c" if (( Z % 5 != 0 )); then echo -e ", \c" else echo -e "" fi (( Z++ ))
done</lang>
<lang bash>for ((i=1;i<=10;i++)); do
echo -n $i if [ $((i%5)) -eq 0 ]; then echo continue fi echo -n ", "
done</lang>
Vedit macro language
<lang vedit>for (#1 = 1; #1 <= 10; #1++) {
Num_Type(#1, LEFT+NOCR) if (#1 % 5 == 0) { Type_Newline Continue } Message(", ")
}</lang>
Visual Basic .NET
<lang vbnet>For i = 1 To 10
Console.Write(i) If i Mod 5 = 0 Then Console.WriteLine() Else Console.Write(", ") End If
Next</lang>
- Programming Tasks
- Iteration
- Ada
- Aikido
- ALGOL 68
- AutoHotkey
- AWK
- Bc
- C
- C++
- C sharp
- Clojure
- ColdFusion
- Common Lisp
- D
- Dc
- Delphi
- Ela
- Factor
- Fantom
- Forth
- Fortran
- GAP
- GML
- Go
- Groovy
- Haskell
- HicEst
- Icon
- Unicon
- J
- Java
- JavaScript
- Lisaac
- Lua
- Mathematica
- MAXScript
- Metafont
- Modula-3
- MOO
- OCaml
- Octave
- Oz
- PARI/GP
- Perl
- Perl 6
- PHP
- PicoLisp
- Pike
- PL/I
- Pop11
- PowerShell
- PureBasic
- Python
- R
- REBOL
- REXX
- Ruby
- Sather
- Scheme
- Suneido
- Tcl
- TI-89 BASIC
- TUSCRIPT
- UnixPipes
- UNIX Shell
- Vedit macro language
- Visual Basic .NET
- M4/Omit
- Loop modifiers