Determine if a string has all the same characters: Difference between revisions

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Task

Given a character string (which may be empty, or have a length of zero characters):

create a function/procedure/routine to:

determine if all the characters in the string are the same
indicate if or which character is different from the previous character

display each string and its length (as the strings are being examined)
a zero─length (empty) string shall be considered as all the same character(s)
process the strings from left─to─right
if all the same character, display a message saying such
if not all the same character, then:

display a message saying such
display what character is different
only the 1^st different character need be displayed
display where the different character is in the string
the above messages can be part of a single message
display the hexadecimal value of the different character

Use (at least) these seven test values (strings):

a string of length 0 (an empty string)
a string of length 3 which contains three blanks
a string of length 1 which contains: 2
a string of length 3 which contains: 333
a string of length 3 which contains: .55
a string of length 6 which contains: tttTTT
a string of length 9 with a blank in the middle: 4444 444k

Show all output here on this page.

Other tasks related to string operations:

Metrics

Counting

Remove/replace

Anagrams/Derangements/shuffling

Find/Search/Determine

Formatting

Song lyrics/poems/Mad Libs/phrases

Tokenize

Sequences

11l

Translation of: Kotlin

<lang 11l>F analyze(s)

  print(‘Examining [’s‘] which has a length of ’s.len‘:’)
  I s.len > 1
     V b = s[0]
     L(c) s
        V i = L.index
        I c != b
           print(‘    Not all characters in the string are the same.’)
           print(‘    '’c‘' (0x’hex(c.code)‘) is different at position ’i)
           R

  print(‘    All characters in the string are the same.’)

V strs = [‘’, ‘ ’, ‘2’, ‘333’, ‘.55’, ‘tttTTT’, ‘4444 444k’] L(s) strs

  analyze(s)</lang>

Output:

Examining [] which has a length of 0:
    All characters in the string are the same.
Examining [   ] which has a length of 3:
    All characters in the string are the same.
Examining [2] which has a length of 1:
    All characters in the string are the same.
Examining [333] which has a length of 3:
    All characters in the string are the same.
Examining [.55] which has a length of 3:
    Not all characters in the string are the same.
    '5' (0x35) is different at position 1
Examining [tttTTT] which has a length of 6:
    Not all characters in the string are the same.
    'T' (0x54) is different at position 3
Examining [4444 444k] which has a length of 9:
    Not all characters in the string are the same.
    ' ' (0x20) is different at position 4

Ada

<lang Ada>with Ada.Integer_Text_IO; use Ada.Integer_Text_IO; with Ada.Text_IO; use Ada.Text_IO; procedure Test_All_Chars_Are_Same is

  procedure All_Chars_Are_Same (S : in String) is
     First_Diff : Natural := 0;
  begin
     Put_Line ("Input = """ & S & """, length =" & S'Length'Image);
     for I in S'First + 1 .. S'Last loop
        if S(I) /= S(S'First) then
           First_Diff := I;
           exit;
        end if;
     end loop;
     if First_Diff = 0 then
        Put_Line (" All characters are the same.");
     else
        Put (" First difference at position" & First_Diff'Image &
             ", character = '" & S(First_Diff) &
             "', hex = ");
        Put (Character'Pos (S(First_Diff)), Width => 0, Base => 16);
        New_Line;
     end if;
  end All_Chars_Are_Same;

begin

  All_Chars_Are_Same ("");
  All_Chars_Are_Same ("   ");
  All_Chars_Are_Same ("2");
  All_Chars_Are_Same ("333");
  All_Chars_Are_Same (".55");
  All_Chars_Are_Same ("tttTTT");
  All_Chars_Are_Same ("4444 444k");

end Test_All_Chars_Are_Same;</lang>

Output:

Input = "", length = 0
 All characters are the same.
Input = "   ", length = 3
 All characters are the same.
Input = "2", length = 1
 All characters are the same.
Input = "333", length = 3
 All characters are the same.
Input = ".55", length = 3
 First difference at position 2, character = '5', hex = 16#35#
Input = "tttTTT", length = 6
 First difference at position 4, character = 'T', hex = 16#54#
Input = "4444 444k", length = 9
 First difference at position 5, character = ' ', hex = 16#20#

ALGOL 68

<lang algol68>BEGIN

   # return the position of the first different character in s           #
   #     or UPB s + 1 if all the characters are the same                 #
   OP  FIRSTDIFF = ( STRING s )INT:
       IF UPB s <= LWB s
       THEN
           # 0 or 1 character                                            #
           UPB s + 1
       ELSE
           # two or more characters                                      #
           INT  result := LWB s + 1;
           CHAR c1      = s[ LWB s ];
           FOR s pos FROM LWB s + 1 TO UPB s WHILE s[ s pos ] = c1 DO result +:= 1 OD;
           result
       FI # FIRSTDIFF # ;
   # convert a character to a hex string                                 #
   PROC hex = ( CHAR c )STRING:
       BEGIN
           STRING result := "";
           INT    n      := ABS c;
           IF n = 0
           THEN
               result := "0"
           ELSE
               WHILE n > 0 DO
                   INT d = n MOD 16;
                   n OVERAB 16;
                   IF d < 10
                   THEN REPR ( d + ABS "0" )
                   ELSE REPR ( ( d - 10 ) + ABS "0" )
                   FI +=: result
               OD
           FI;
           result
       END # hex # ;
   # show whether s contains all the same character of the first diff    #
   PROC show first diff = ( STRING s )VOID:
       IF  print( ( """", s, """ (length ", whole( ( UPB s + 1 ) - LWB s, 0 ), "): " ) );
           INT diff pos = FIRSTDIFF s;
           diff pos > UPB s
       THEN
           # all characters the same                                     #
           print( ( "all characters are the same", newline ) )
       ELSE
           # not all characters are the same                             #
           print( ( "first different character """
                  , s[ diff pos ]
                  , """(0x", hex( s[ diff pos ] )
                  , ") at position: "
                  , whole( diff pos, 0 )
                  , newline
                  )
                )
       FI # show first diff # ;
   # task test cases                                                     #
   show first diff( ""          );
   show first diff( "   "       );
   show first diff( "2"         );
   show first diff( "333"       );
   show first diff( ".55"       );
   show first diff( "tttTTT"    );
   show first diff( "4444 444k" )

END</lang>

Output:

"" (length 0): all characters are the same
"   " (length 3): all characters are the same
"2" (length 1): all characters are the same
"333" (length 3): all characters are the same
".55" (length 3): first different character "5"(0x35) at position: 2
"tttTTT" (length 6): first different character "T"(0x54) at position: 4
"4444 444k" (length 9): first different character " "(0x20) at position: 5

Arturo

<lang rebol>strings: [

   "", "   ", "2", "333", ".55", "tttTTT", 
   "4444   444k", "pépé", "🐶🐶🐺🐶", "🎄🎄🎄🎄"

]

allSameChars?: function [str][

   if empty? str -> return ø
   current: first str
   loop.with:'i str 'ch [
       if ch <> current -> return i
   ]
   return ø

]

loop strings 's [

   prints ["\"" ++ s ++ "\"" ~"(size |size s|):"]
   firstNotSame: allSameChars? s
   if? null? firstNotSame -> print "all the same."
   else -> print ~"first different char `|get s firstNotSame|` at position |firstNotSame|."

]</lang>

Output:

"" (size 0): all the same.
"   " (size 3): all the same.
"2" (size 1): all the same.
"333" (size 3): all the same.
".55" (size 3): first different char `5` at position 1.
"tttTTT" (size 6): first different char `T` at position 3.
"4444   444k" (size 11): first different char ` ` at position 4.
"pépé" (size 4): first different char `é` at position 1.
"🐶🐶🐺🐶" (size 4): first different char `🐺` at position 2.
"🎄🎄🎄🎄" (size 4): all the same.

<lang AutoHotkey>testCases := ["", " ", "2", "333", ".55", "tttTTT", "4444 4444k"] for key, str in testCases { MsgBox % "Examining `'" str "`' which has a length of " StrLen(str) ":`n" if (StrLen(str) == 0) or (StrLen(str) == 1) { MsgBox % " All characters in the string are the same.`n" continue } firstChar := SubStr(str, 1, 1) Loop, Parse, str { if (firstChar != A_LoopField) { hex := Format("0x{:x}", Ord(A_LoopField)) MsgBox % " Not all characters in the string are the same.`n Character `'" A_LoopField "`' (" hex ") is different at position " A_Index ".`n", * break } if (A_Index = StrLen(str)) MsgBox % " All characters in the string are the same.`n", * } } </lang>

Output:

Examining '' which has a length of 0:
    All characters in the string are the same.
Examining '   ' which has a length of 3:
    All characters in the string are the same.
Examining '2' which has a length of 1:
    All characters in the string are the same.
Examining '333' which has a length of 3:
    All characters in the string are the same.
Examining '.55' which has a length of 3:
    Not all characters in the string are the same.
    Character '5' (0x35) is different at position 2.
Examining 'tttTTT' which has a length of 6:
    All characters in the string are the same.
Examining '4444 4444k' which has a length of 10:
    Not all characters in the string are the same.
    Character ' ' (0x20) is different at position 5.

AWK

syntax: GAWK -f DETERMINE_IF_A_STRING_HAS_ALL_THE_SAME_CHARACTERS.AWK

BEGIN {

   for (i=0; i<=255; i++) { ord_arr[sprintf("%c",i)] = i } # build array[character]=ordinal_value
   n = split(",   ,2,333,.55,tttTTT,4444 444k",arr,",")
   for (i in arr) {
     width = max(width,length(arr[i]))
   }
   width += 2
   fmt = "| %-*s | %-6s | %-8s | %-8s | %-3s | %-8s |\n"
   head1 = head2 = sprintf(fmt,width,"string","length","all same","1st diff","hex","position")
   gsub(/[^|\n]/,"-",head1)
   printf(head1 head2 head1) # column headings
   for (i=1; i<=n; i++) {
     main(arr[i])
   }
   printf(head1) # column footing
   exit(0)

} function main(str, c,first_diff,hex,i,leng,msg,position) {

   msg = "yes"
   leng = length(str)
   for (i=1; i<leng; i++) {
     c = substr(str,i+1,1)
     if (substr(str,i,1) != c) {
       msg = "no"
       first_diff = "'" c "'"
       hex = sprintf("%2X",ord_arr[c])
       position = i + 1
       break
     }
   }
   printf(fmt,width,"'" str "'",leng,msg,first_diff,hex,position)

} function max(x,y) { return((x > y) ? x : y) } </lang>

Output:

|-------------|--------|----------|----------|-----|----------|
| string      | length | all same | 1st diff | hex | position |
|-------------|--------|----------|----------|-----|----------|
| ''          | 0      | yes      |          |     |          |
| '   '       | 3      | yes      |          |     |          |
| '2'         | 1      | yes      |          |     |          |
| '333'       | 3      | yes      |          |     |          |
| '.55'       | 3      | no       | '5'      | 35  | 2        |
| 'tttTTT'    | 6      | no       | 'T'      | 54  | 4        |
| '4444 444k' | 9      | no       | ' '      | 20  | 5        |
|-------------|--------|----------|----------|-----|----------|

BASIC

GWBASIC

Works with BASICA <lang GWBASIC> 10 'SAVE"SAMECHAR", A 20 DEFINT A-Z 30 DATA ""," ","2","333",".55","tttTTT","4444 444k", "FIN" 40 ' Main program cycle 50 CLS 60 PRINT "Program SameChar" 70 PRINT "Determines if a string has the same character or not." 80 PRINT 90 WHILE S$<>"FIN" 100 READ S$ 110 IF S$="FIN" THEN 150 120 GOSUB 190 ' Revision subroutine 130 PRINT "'";S$;"' of length";LEN(S$); 140 IF I<2 THEN PRINT "contains all the same character." ELSE PRINT "is different at possition";STR$(I);": '";DC$; "' (0x"; HEX$(ASC(DC$)); ")" 150 WEND 160 PRINT 170 PRINT "End of program run." 180 END 190 ' DifChar subroutine 200 C$ = LEFT$(S$,1) 210 I = 1 220 DC$="" 230 WHILE I<LEN(S$) AND DC$="" 240 IF MID$(S$,I,1)<>C$ THEN DC$=MID$(S$,I,1) ELSE I=I+1 250 WEND 260 IF DC$="" THEN I=1 270 RETURN</lang>

Output:

Program SameChar
Determines if a string has the same character or not.

'' of length 0 contains all the same character.
'   ' of length 3 contains all the same character.
'2' of length 1 contains all the same character.
'333' of lenght 3 contains all the same character.
'.55' of length 3 is different at possition 2: '5' (0x35)
'tttTTT' of length 6 is different at possition 4: 'T' (0x54)
'4444 444k' of length 9 is different at possition 5: ' ' (0x20)

End of program run.

QuickBASIC

Works with QBASIC, VB-DOS, PDS 7.x <lang QBASIC> DECLARE SUB DifChar (sString AS STRING, wc AS INTEGER, dc AS STRING)

DIM i AS INTEGER DIM s AS STRING DIM dc AS STRING

DATA "", " ", "2", "333",".55","tttTTT", "4444 444k", "FIN"

' Main program cycle CLS PRINT "Program SameChar" PRINT "Determines if a string has the same character or not." PRINT DO

 READ s
 IF s = "FIN" THEN EXIT DO
 DifChar s, i, dc
 PRINT "'"; s; "' of length"; LEN(s);
 IF i < 2 THEN
   PRINT "contains all the same character."
 ELSE
   PRINT "is different at possition"; STR$(i); ": '"; dc; "' (0x"; HEX$(ASC(dc)); ")"
 END IF

LOOP PRINT PRINT "End of program run." END

SUB DifChar (sString AS STRING, wc AS INTEGER, dc AS STRING)

 ' Var
 DIM c AS STRING

 ' Look for the distinct char
 c = LEFT$(sString, 1)
 wc = 1
 dc = ""
 DO WHILE wc < LEN(sString)
   IF MID$(sString, wc, 1) <> c THEN dc = MID$(sString, wc, 1): EXIT DO
   wc = wc + 1
 LOOP

 IF dc = "" THEN wc = 1

END SUB

</lang>

Output:

Program SameChar
Determines if a string has the same character or not.

'' of length 0 contains all the same character.
'   ' of length 3 contains all the same character.
'2' of length 1 contains all the same character.
'333' of lenght 3 contains all the same character.
'.55' of length 3 is different at possition 2: '5' (0x35)
'tttTTT' of length 6 is different at possition 4: 'T' (0x54)
'4444 444k' of length 9 is different at possition 5: ' ' (0x20)

End of program run.

BCPL

<lang bcpl>get "libhdr"

let diffchar(s) = valof $( for i=2 to s%0

       unless s%i = s%1 resultis i
   resultis 0

$)

let show(s) be $( let i = diffchar(s)

   writef("*"%S*" (length %N): ", s, s%0)
   test i=0
       do writes("all the same.*N")
       or writef("'%C' at index %N.*N", s%i, i)

$)

let start() be $( show("")

   show("   ")
   show("2")
   show("333")
   show(".55")
   show("tttTTT")
   show("4444 444k")

$)</lang>

Output:

"" (length 0): all the same.
"   " (length 3): all the same.
"2" (length 1): all the same.
"333" (length 3): all the same.
".55" (length 3): '5' at index 2.
"tttTTT" (length 6): 'T' at index 4.
"4444 444k" (length 9): ' ' at index 5.

C

Solution with an index to a table

In interactive mode, strings with spaces have to be enclosed in double quotes ("") <lang C>

include<string.h>
include<stdio.h>

int main(int argc,char** argv) {

   int i,len;
   char reference;
   
   if(argc>2){
       printf("Usage : %s <Test String>\n",argv[0]);
       return 0;
   }

   if(argc==1||strlen(argv[1])==1){
       printf("Input string : \"%s\"\nLength : %d\nAll characters are identical.\n",argc==1?"":argv[1],argc==1?0:(int)strlen(argv[1]));
       return 0;
   }

   reference = argv[1][0];
   len = strlen(argv[1]);

   for(i=1;i<len;i++){
       if(argv[1][i]!=reference){
           printf("Input string : \"%s\"\nLength : %d\nFirst different character : \"%c\"(0x%x) at position : %d\n",argv[1],len,argv[1][i],argv[1][i],i+1);
           return 0;
       }
   }

   printf("Input string : \"%s\"\nLength : %d\nAll characters are identical.\n",argv[1],len);

   return 0;

} </lang> Output :

abhishek_ghosh@Azure:~/doodles$ ./a.out
Input string : ""
Length : 0
All characters are identical.
abhishek_ghosh@Azure:~/doodles$ ./a.out "   "
Input string : "   "
Length : 3
All characters are identical.
abhishek_ghosh@Azure:~/doodles$ ./a.out 2
Input string : "2"
Length : 1
All characters are identical.
abhishek_ghosh@Azure:~/doodles$ ./a.out 333
Input string : "333"
Length : 3
All characters are identical.
abhishek_ghosh@Azure:~/doodles$ ./a.out .55
Input string : ".55"
Length : 3
First different character : "5"(0x35) at position : 2
abhishek_ghosh@Azure:~/doodles$ ./a.out tttTTT
Input string : "tttTTT"
Length : 6
First different character : "T"(0x54) at position : 4
abhishek_ghosh@Azure:~/doodles$ ./a.out "4444 444k"
Input string : "4444 444k"
Length : 9
First different character : " "(0x20) at position : 5

Solution with pointers

<lang C>/**

* An example for RossetaCode - an example of string operation with wchar_t and
* with old 8-bit characters. Anyway, it seem that C is not very UTF-8 friendly,
* thus C# or C++ may be a better choice.
*/

include <stdio.h>
include <stdlib.h>
include <string.h>

/*

* The wide character version of the program is compiled if WIDE_CHAR is defined
*/

define WIDE_CHAR

ifdef WIDE_CHAR
define CHAR wchar_t
else
define CHAR char
endif

/**

* Find a character different from the preceding characters in the given string.
* 
* @param s the given string, NULL terminated.
* 
* @return the pointer to the occurence of the different character or NULL if
*         all characters in the string are exactly the same.
* 
* @notice This function return NULL also for empty strings.
* 
* @warning This function compare characters (single-bytes, unicode etc.).
*          Therefore this is not designed to compare bytes. The NULL character
*          is always treated as the end-of-string marker, thus this function
*          cannot be used to scan strings with NULL character inside string,
*          for an example "aaa\0aaa\0\0".
*/

const CHAR* find_different_char(const CHAR* s) {

   /* The code just below is almost the same regardles 
      char or wchar_t is used. */

   const CHAR c = *s;
   while (*s && c == *s)
   {
       s++;
   }
   return s;

}

/**

* Apply find_different_char function to a given string and output the raport.
* 
* @param s the given NULL terminated string.
*/

void raport_different_char(const CHAR* s) {

ifdef WIDE_CHAR

   wprintf(L"\n");
   wprintf(L"string: \"%s\"\n", s);
   wprintf(L"length: %d\n", wcslen(s));
   const CHAR* d = find_different_char(s);
   if (d)
   {
       /*
        * We have got the famous pointers arithmetics and we can compute
        * difference of pointers pointing to the same array.
        */
       wprintf(L"character '%wc' (%#x) at %d\n", *d, *d, (int)(d - s));
   }
   else
   {
       wprintf(L"all characters are the same\n");
   }
   wprintf(L"\n");

else

   putchar('\n');
   printf("string: \"%s\"\n", s);
   printf("length: %d\n", strlen(s));
   const CHAR* d = find_different_char(s);
   if (d)
   { 
       /*
        * We have got the famous pointers arithmetics and we can compute
        * difference of pointers pointing to the same array.
        */
       printf("character '%c' (%#x) at %d\n", *d, *d, (int)(d - s));
   }
   else
   {
       printf("all characters are the same\n");
   }
   putchar('\n');

endif

}

/* There is a wmain function as an entry point when argv[] points to wchar_t */

ifdef WIDE_CHAR

int wmain(int argc, wchar_t* argv[])

else

int main(int argc, char* argv[])

endif

{

   if (argc < 2)
   {
       raport_different_char(L"");
       raport_different_char(L"   ");
       raport_different_char(L"2");
       raport_different_char(L"333");
       raport_different_char(L".55");
       raport_different_char(L"tttTTT");
       raport_different_char(L"4444 444k");
   }
   else
   {
       raport_different_char(argv[1]);
   }

   return EXIT_SUCCESS;

}</lang>

Output:

string: ""
length: 0
all characters are the same


string: "   "
length: 3
all characters are the same


string: "2"
length: 1
all characters are the same


string: "333"
length: 3
all characters are the same


string: ".55"
length: 3
character '5' (0x35) at 1


string: "tttTTT"
length: 6
character 'T' (0x54) at 3


string: "4444 444k"
length: 9
character ' ' (0x20) at 4

C#

Translation of: D

<lang csharp>using System;

namespace AllSame {

   class Program {
       static void Analyze(string s) {
           Console.WriteLine("Examining [{0}] which has a length of {1}:", s, s.Length);
           if (s.Length > 1) {
               var b = s[0];
               for (int i = 1; i < s.Length; i++) {
                   var c = s[i];
                   if (c != b) {
                       Console.WriteLine("    Not all characters in the string are the same.");
                       Console.WriteLine("    '{0}' (0x{1:X02}) is different at position {2}", c, (int)c, i);
                       return;
                   }
               }

           }
           Console.WriteLine("    All characters in the string are the same.");
       }

       static void Main() {
           var strs = new string[] { "", "   ", "2", "333", ".55", "tttTTT", "4444 444k" };
           foreach (var str in strs) {
               Analyze(str);
           }
       }
   }

}</lang>

Output:

Examining [] which has a length of 0:
    All characters in the string are the same.
Examining [   ] which has a length of 3:
    All characters in the string are the same.
Examining [2] which has a length of 1:
    All characters in the string are the same.
Examining [333] which has a length of 3:
    All characters in the string are the same.
Examining [.55] which has a length of 3:
    Not all characters in the string are the same.
    '5' (0x35) is different at position 1
Examining [tttTTT] which has a length of 6:
    Not all characters in the string are the same.
    'T' (0x54) is different at position 3
Examining [4444 444k] which has a length of 9:
    Not all characters in the string are the same.
    ' ' (0x20) is different at position 4

C++

<lang cpp>#include <iostream>

include <string>

void all_characters_are_the_same(const std::string& str) {

   size_t len = str.length();
   std::cout << "input: \"" << str << "\", length: " << len << '\n';
   if (len > 0) {
       char ch = str[0];
       for (size_t i = 1; i < len; ++i) {
           if (str[i] != ch) {
               std::cout << "Not all characters are the same.\n";
               std::cout << "Character '" << str[i]
                   << "' (hex " << std::hex << static_cast<unsigned int>(str[i])
                   << ") at position " << std::dec << i + 1
                   << " is not the same as '" << ch << "'.\n\n";
               return;
           }
       }
   }
   std::cout << "All characters are the same.\n\n";

}

int main() {

   all_characters_are_the_same("");
   all_characters_are_the_same("   ");
   all_characters_are_the_same("2");
   all_characters_are_the_same("333");
   all_characters_are_the_same(".55");
   all_characters_are_the_same("tttTTT");
   all_characters_are_the_same("4444 444k");
   return 0;

}</lang>

Output:

input: "", length: 0
All characters are the same.

input: "   ", length: 3
All characters are the same.

input: "2", length: 1
All characters are the same.

input: "333", length: 3
All characters are the same.

input: ".55", length: 3
Not all characters are the same.
Character '5' (hex 35) at position 2 is not the same as '.'.

input: "tttTTT", length: 6
Not all characters are the same.
Character 'T' (hex 54) at position 4 is not the same as 't'.

input: "4444 444k", length: 9
Not all characters are the same.
Character ' ' (hex 20) at position 5 is not the same as '4'.

Clojure

<lang Clojure> (defn check-all-chars-same [s]

 (println (format "String (%s) of len: %d" s (count s)))
 (let [num-same (-> (take-while #(= (first s) %) s)
                    count)]
   (if (= num-same (count s))
     (println "...all characters the same")
     (println (format "...character %d differs - it is 0x%x"
                      num-same
                      (byte (nth s num-same)))))))

 (map check-all-chars-same
        [""
         "   "
         "2"
         "333"
         ".55"
         "tttTTT"
         "4444 444k"])

</lang>

Output:

(String () of len: 0
...all characters the same
String (   ) of len: 3
...all characters the same
String (2) of len: 1
...all characters the same
String (333) of len: 3
...all characters the same
String (.55) of len: 3
...character 1 differs - it is 0x35
String (tttTTT) of len: 6
...character 3 differs - it is 0x54
String (4444 444k) of len: 9
...character 4 differs - it is 0x20

Common Lisp

Usage : (strequ string(s)) or (strequ) for auto-test

<lang lisp>(defun strequ (&rest str)

   (if (not str) (setf str (list "" "   " "2" "333" ".55" "tttTTT" "4444 444k")))
   (dolist (s str)
       (do ((i 0 (1+ i)))
           ((cond
               ((= i (length s))
                   (format t "\"~a\" [~d] : All characters are identical.~%" s (length s)) t)
               ((char/= (char s i) (char s 0))
                   (format t "\"~a\" [~d] : '~c' (0x~0x) at index ~d is different.~%" s (length s) (char s i) (char-int (char s i)) i) t))))))</lang>

Output:

"" [0] : All characters are identical.
"   " [3] : All characters are identical.
"2" [1] : All characters are identical.
"333" [3] : All characters are identical.
".55" [3] : '5' (0x35) at index 1 is different.
"tttTTT" [6] : 'T' (0x54) at index 3 is different.
"4444 444k" [9] : ' ' (0x20) at index 4 is different.

D

Translation of: Kotlin

<lang d>import std.stdio;

void analyze(string s) {

   writefln("Examining [%s] which has a length of %d:", s, s.length);
   if (s.length > 1) {
       auto b = s[0];
       foreach (i, c; s[1..$]) {
           if (c != b) {
               writeln("    Not all characters in the string are the same.");
               writefln("    '%c' (0x%x) is different at position %d", c, c, i);
               return;
           }
       }
   }
   writeln("    All characters in the string are the same.");

}

void main() {

   auto strs = ["", "   ", "2", "333", ".55", "tttTTT", "4444 444k"];
   foreach (str; strs) {
       analyze(str);
   }

}</lang>

Output:

Examining [] which has a length of 0:
    All characters in the string are the same.
Examining [   ] which has a length of 3:
    All characters in the string are the same.
Examining [2] which has a length of 1:
    All characters in the string are the same.
Examining [333] which has a length of 3:
    All characters in the string are the same.
Examining [.55] which has a length of 3:
    Not all characters in the string are the same.
    '5' (0x35) is different at position 0
Examining [tttTTT] which has a length of 6:
    Not all characters in the string are the same.
    'T' (0x54) is different at position 2
Examining [4444 444k] which has a length of 9:
    Not all characters in the string are the same.
    ' ' (0x20) is different at position 3

Delphi

Library: System.SysUtils

Translation of: D

<lang Delphi> program Determine_if_a_string_has_all_the_same_characters;

{$APPTYPE CONSOLE}

uses

 System.SysUtils;

procedure Analyze(s: string); var

 b, c: char;
 i: Integer;

begin

 writeln(format('Examining [%s] which has a length of %d:', [s, s.Length]));
 if s.Length > 1 then
 begin
   b := s[1];
   for i := 2 to s.Length - 1 do
   begin
     c := s[i];
     if c <> b then
     begin
       writeln('    Not all characters in the string are the same.');
       writeln(format('    "%s" 0x%x is different at position %d', [c, Ord(c), i]));
       Exit;
     end;
   end;
 end;
 writeln('    All characters in the string are the same.');

end;

var

 TestCases: array of string = [, '   ', '2', '333', '.55', 'tttTTT', '4444 444k'];
 w: string;

begin

 for w in TestCases do
   Analyze(w);
 Readln;

end.</lang>

Output:

Examining [] which has a length of 0:
    All characters in the string are the same.
Examining [   ] which has a length of 3:
    All characters in the string are the same.
Examining [2] which has a length of 1:
    All characters in the string are the same.
Examining [333] which has a length of 3:
    All characters in the string are the same.
Examining [.55] which has a length of 3:
    Not all characters in the string are the same.
    "5" 0x35 is different at position 2
Examining [tttTTT] which has a length of 6:
    Not all characters in the string are the same.
    "T" 0x54 is different at position 4
Examining [4444 444k] which has a length of 9:
    Not all characters in the string are the same.
    " " 0x20 is different at position 5

F#

<lang fsharp> // Determine if a string has all the same characters. Nigel Galloway: June 9th., 2020 let fN n=if String.length n=0 then None else n.ToCharArray()|>Array.tryFindIndex(fun g->g<>n.[0])

let allSame n=match fN n with

              Some g->printfn "First different character in <<<%s>>> (length %d) is hex %x at position %d" n n.Length (int n.[g]) g
             |_->printfn "All Characters are the same in <<<%s>>> (length %d)" n n.Length

allSame "" allSame " " allSame "2" allSame "333" allSame ".55" allSame "tttTTT" allSame "4444 444k" </lang>

Output:

All Characters are the same in <<<>>> (length 0)
All Characters are the same in <<<   >>> (length 3)
All Characters are the same in <<<2>>> (length 1)
All Characters are the same in <<<333>>> (length 3)
First different character in <<<.55>>> (length 3) is hex 35 at position 1
First different character in <<<tttTTT>>> (length 6) is hex 54 at position 3
First different character in <<<4444 444k>>> (length 9) is hex 20 at position 4

Factor

<lang factor>USING: formatting io kernel math.parser sequences ;

find-diff ( str -- i elt ) dup ?first [ = not ] curry find ;

len. ( str -- ) dup length "%u — length %d — " printf ;

same. ( -- ) "contains all the same character." print ;

diff. ( -- ) "contains a different character at " write ;

not-same. ( i elt -- )

   dup >hex diff. "index %d: '%c' (0x%s)\n" printf ;

sameness-report. ( str -- )

   dup len. find-diff dup [ not-same. ] [ 2drop same. ] if ;

{

   ""
   "   "
   "2"
   "333"
   ".55"
   "tttTTT"
   "4444 444k"

} [ sameness-report. ] each</lang>

Output:

"" — length 0 — contains all the same character.
"   " — length 3 — contains all the same character.
"2" — length 1 — contains all the same character.
"333" — length 3 — contains all the same character.
".55" — length 3 — contains a different character at index 1: '5' (0x35)
"tttTTT" — length 6 — contains a different character at index 3: 'T' (0x54)
"4444 444k" — length 9 — contains a different character at index 4: ' ' (0x20)

FreeBASIC

<lang freebasic>dim as string s, nxt

input "Enter string: ", s

if len(s)<2 then 'A string with one or zero characters passes by default

   print "All characters are the same."
   end

end if

dim as ubyte i

for i = 1 to len(s)-1

   nxt = mid(s, i+1, 1)
   if mid(s, i, 1)<>nxt then   'if any character differs from the previous one
       print "First non-matching char is "+nxt
       print "It occurs at position "+str(i+1)
       print "Its hex value is "+hex(asc(nxt))
       end
   end if

next i

'otherwise, success! print "All characters are the same."</lang>

Output:

Enter string:  
All characters are the same.

Enter string:     
All characters are the same.

Enter string:  2
All characters are the same.

Enter string:  333
All characters are the same.

Enter string:  .55
First non-matching char is 5
It occurs at position 2
Its hex value is 35

Enter string:  tttTTT
First non-matching char is T
It occurs at position 4
Its hex value is 54

Enter string:  4444 444k
First non-matching char is  
It occurs at position 5
Its hex value is 20

Go

<lang go>package main

import "fmt"

func analyze(s string) {

   chars := []rune(s)
   le := len(chars)
   fmt.Printf("Analyzing %q which has a length of %d:\n", s, le)
   if le > 1 {
       for i := 1; i < le; i++ {
           if chars[i] != chars[i-1] {
               fmt.Println("  Not all characters in the string are the same.")
               fmt.Printf("  %q (%#[1]x) is different at position %d.\n\n", chars[i], i+1)
               return
           }
       }
   }
   fmt.Println("  All characters in the string are the same.\n")

}

func main() {

   strings := []string{
       "",
       "   ",
       "2",
       "333",
       ".55",
       "tttTTT",
       "4444 444k",
       "pépé",
       "🐶🐶🐺🐶",
       "🎄🎄🎄🎄",
   }
   for _, s := range strings {
       analyze(s)
   }

}</lang>

Output:

Analyzing "" which has a length of 0:
  All characters in the string are the same.

Analyzing "   " which has a length of 3:
  All characters in the string are the same.

Analyzing "2" which has a length of 1:
  All characters in the string are the same.

Analyzing "333" which has a length of 3:
  All characters in the string are the same.

Analyzing ".55" which has a length of 3:
  Not all characters in the string are the same.
  '5' (0x35) is different at position 2.

Analyzing "tttTTT" which has a length of 6:
  Not all characters in the string are the same.
  'T' (0x54) is different at position 4.

Analyzing "4444 444k" which has a length of 9:
  Not all characters in the string are the same.
  ' ' (0x20) is different at position 5.

Analyzing "pépé" which has a length of 4:
  Not all characters in the string are the same.
  'é' (0xe9) is different at position 2.

Analyzing "🐶🐶🐺🐶" which has a length of 4:
  Not all characters in the string are the same.
  '🐺' (0x1f43a) is different at position 3.

Analyzing "🎄🎄🎄🎄" which has a length of 4:
  All characters in the string are the same.

Groovy

Translation of: Java

<lang groovy>class Main {

   static void main(String[] args) {
       String[] tests = ["", "   ", "2", "333", ".55", "tttTTT", "4444 444k"]
       for (String s : tests) {
           analyze(s)
       }
   }

   static void analyze(String s) {
       println("Examining [$s] which has a length of ${s.length()}")
       if (s.length() > 1) {
           char firstChar = s.charAt(0)
           int lastIndex = s.lastIndexOf(firstChar as String)
           if (lastIndex != 0) {
               println("\tNot all characters in the string are the same.")
               println("\t'$firstChar' (0x${Integer.toHexString(firstChar as Integer)}) is different at position $lastIndex")
               return
           }
       }
       println("\tAll characters in the string are the same.")
   }

}</lang>

Output:

Examining [] which has a length of 0
	All characters in the string are the same.
Examining [   ] which has a length of 3
	Not all characters in the string are the same.
	' ' (0x20) is different at position 2
Examining [2] which has a length of 1
	All characters in the string are the same.
Examining [333] which has a length of 3
	Not all characters in the string are the same.
	'3' (0x33) is different at position 2
Examining [.55] which has a length of 3
	All characters in the string are the same.
Examining [tttTTT] which has a length of 6
	Not all characters in the string are the same.
	't' (0x74) is different at position 2
Examining [4444 444k] which has a length of 9
	Not all characters in the string are the same.
	'4' (0x34) is different at position 7

Haskell

<lang haskell>import Numeric (showHex) import Data.List (span) import Data.Char (ord)

inconsistentChar :: Eq a => [a] -> Maybe (Int, a) inconsistentChar [] = Nothing inconsistentChar xs@(x:_) =

 let (pre, post) = span (x ==) xs
 in if null post
      then Nothing
      else Just (length pre, head post)

TEST----------------------------

samples :: [String] samples = [" ", "2", "333", ".55", "tttTTT", "4444 444"]

main :: IO () main = do

 let w = succ . maximum $ length <$> samples
     justifyRight n c = (drop . length) <*> (replicate n c ++)
     f = (++ "' -> ") . justifyRight w ' ' . ('\ :)
 (putStrLn . unlines) $
   (\s ->
       maybe
         (f s ++ "consistent")
         (\(n, c) ->
             f s ++
             "inconsistent '" ++
             c : "' (0x" ++ showHex (ord c) ")" ++ " at char " ++ show (succ n))
         (inconsistentChar s)) <$>
   samples</lang>

and inconsistentChar could alternatively be defined in terms of findIndex:

<lang haskell>import Data.List (findIndex)

inconsistentChar :: Eq a => [a] -> Maybe (Int, a) inconsistentChar [] = Nothing inconsistentChar xs@(x:_) = findIndex (x /=) xs >>= Just . ((,) <*> (xs !!))</lang>

Output:

     '   ' -> consistent
       '2' -> consistent
     '333' -> consistent
     '.55' -> inconsistent '5' (0x35) at char 2
  'tttTTT' -> inconsistent 'T' (0x54) at char 4
'4444 444' -> inconsistent ' ' (0x20) at char 5

J

<lang> Doc=: 2 : 'u :: (n"_)'

task=: monad define

common=. (; #) y  NB. the string and its length
if. same y do.
 common , <'same'
else.
 i =. differ y
 c =. i { y
 common , <((, (' (' , ') ' ,~ hex))c),'differs at index ',":i
end.

)

hex=: ((Num_j_,26}.Alpha_j_) {~ 16 16 #: a.&i.)&> Doc 'convert ASCII literals to hex representation' assert '61' -: hex 'a'

</lang>

   STRINGS=: <;._2';   ;2;333;.55;tttTTT;4444 444k;'

   same=: (2 > #@:~.)Doc'is 1 if the set of characters has less than 2 elements'
   assert 1 1 1 1 0 0 0 -: same&>STRINGS


   differ=: ([: >: [: {. [: I. 2 ~:/\ ])Doc'given different characters, return the zero index origin position of the character that differs'
   assert 1 -: differ'abbb'

   task&>STRINGS
+---------+-+-------------------------+
|         |0|same                     |
+---------+-+-------------------------+
|         |3|same                     |
+---------+-+-------------------------+
|2        |1|same                     |
+---------+-+-------------------------+
|333      |3|same                     |
+---------+-+-------------------------+
|.55      |3|5 (35) differs at index 1|
+---------+-+-------------------------+
|tttTTT   |6|T (54) differs at index 3|
+---------+-+-------------------------+
|4444 444k|9|  (20) differs at index 4|
+---------+-+-------------------------+

Java

<lang Java>public class Main{ public static void main(String[] args){ String[] tests = {"", " ", "2", "333", ".55", "tttTTT", "4444 444k"}; for(String s:tests) analyze(s); }

public static void analyze(String s){ System.out.printf("Examining [%s] which has a length of %d:\n", s, s.length()); if(s.length() > 1){ char firstChar = s.charAt(0); int lastIndex = s.lastIndexOf(firstChar); if(lastIndex != 0){ System.out.println("\tNot all characters in the string are the same."); System.out.printf("\t'%c' (0x%x) is different at position %d\n", firstChar, (int) firstChar, lastIndex); return; } } System.out.println("\tAll characters in the string are the same."); } }</lang>

Output:

Examining [] which has a length of 0:
	All characters in the string are the same.
Examining [   ] which has a length of 3:
	Not all characters in the string are the same.
	' ' (0x20) is different at position 2
Examining [2] which has a length of 1:
	All characters in the string are the same.
Examining [333] which has a length of 3:
	Not all characters in the string are the same.
	'3' (0x33) is different at position 2
Examining [.55] which has a length of 3:
	All characters in the string are the same.
Examining [tttTTT] which has a length of 6:
	Not all characters in the string are the same.
	't' (0x74) is different at position 2
Examining [4444 444k] which has a length of 9:
	Not all characters in the string are the same.
	'4' (0x34) is different at position 7

JavaScript

<lang JavaScript>const check = s => {

 const arr = [...s];
 const at = arr.findIndex(
     (v, i) => i === 0 ? false : v !== arr[i - 1]
 )
 const l = arr.length;
 const ok = at === -1;
 const p = ok ? "" : at + 1;
 const v = ok ? "" : arr[at];
 const vs = v === "" ? v : `"${v}"`
 const h = ok ? "" : `0x${v.codePointAt(0).toString(16)}`;
 console.log(`"${s}" => Length:${l}\tSame:${ok}\tPos:${p}\tChar:${vs}\tHex:${h}`)

}

[, ' ', '2', '333', '.55', 'tttTTT', '4444 444k', '🐶🐶🐺🐶', '🎄🎄🎄🎄'].forEach(check)</lang>

Output:


""           => Length:0	Same:true	Pos:	Char:	Hex:
"   "        => Length:3	Same:true	Pos:	Char:	Hex:
"2"          => Length:1	Same:true	Pos:	Char:	Hex:
"333"        => Length:3	Same:true	Pos:	Char:	Hex:
".55"        => Length:3	Same:false	Pos:2	Char:"5"	Hex:0x35
"tttTTT"     => Length:6	Same:false	Pos:4	Char:"T"	Hex:0x54
"4444 444k"  => Length:9	Same:false	Pos:5	Char:" "	Hex:0x20
"🐶🐶🐺🐶"   => Length:4	Same:false	Pos:3	Char:"🐺"	Hex:0x1f43a
"🎄🎄🎄🎄"   => Length:4	Same:true	Pos:	Char:	Hex:

Alternatively, emphasising the composition of generic and reusable (pure value returning) library functions, and remaining agnostic about console.log (which is not part of JavaScript itself – doesn't feature in the ECMAScript standard – and is not available in all JS contexts).

<lang javascript>(() => {

   'use strict';

   // ---------- FIRST INCONSISTENT CHARACTER -----------

   // inconsistentChar :: String -> Maybe (Char, Int)
   const inconsistentChar = s =>
       // Just the first inconsistent character in a
       // string, paired with the index of its position,
       // or Nothing if all of the characters in a string 
       // are the same.
       2 > s.length ? (
           Nothing()
       ) : (() => {
           const [h, ...t] = s;
           const i = t.findIndex(c => h !== c);
           return -1 !== i ? (
               Just([t[i], 1 + i])
           ) : Nothing();
       })();


   // ---------------------- TEST -----------------------
   // main :: IO ()
   const main = () =>
       fTable(
           'First inconsistent character:\n'
       )(
           s => `${quoted("'")(s)} (${[...s].length} chars)`
       )(
           maybe('None')(pair => {
               const c = pair[0];
               return `${quoted("'")(c)} at index ` + (
                   `${pair[1]} (${showHex(ord(c))})`
               );
           })
       )(
           inconsistentChar
       )([
           , '   ', '2', '333', '.55',
           'tttTTT', '4444 444k',
           '🐶🐶🐺🐶', '🎄🎄🎄🎄'
       ]);


   // ----------- REUSABLE GENERIC FUNCTIONS ------------

   // Just :: a -> Maybe a
   const Just = x => ({
       type: 'Maybe',
       Nothing: false,
       Just: x
   });


   // Nothing :: Maybe a
   const Nothing = () => ({
       type: 'Maybe',
       Nothing: true,
   });


   // fTable :: String -> (a -> String) -> 
   // (b -> String) -> (a -> b) -> [a] -> String
   const fTable = s =>
       // Heading -> x display function ->
       //           fx display function ->
       //    f -> values -> tabular string
       xShow => fxShow => f => xs => {
           const
               ys = xs.map(xShow),
               w = Math.max(...ys.map(length));
           return s + '\n' + zipWith(
               a => b => a.padStart(w, ' ') + ' -> ' + b
           )(ys)(
               xs.map(x => fxShow(f(x)))
           ).join('\n');
       };


   // maybe :: b -> (a -> b) -> Maybe a -> b
   const maybe = v =>
       // Default value (v) if m is Nothing, or f(m.Just)
       f => m => m.Nothing ? (
           v
       ) : f(m.Just);


   // showHex :: Int -> String
   const showHex = n =>
       // Hexadecimal string for a given integer.
       '0x' + n.toString(16);


   // length :: [a] -> Int
   const length = xs =>
       // Returns Infinity over objects without finite
       // length. This enables zip and zipWith to choose
       // the shorter argument when one is non-finite,
       // like cycle, repeat etc
       'GeneratorFunction' !== xs.constructor
       .constructor.name ? (
           xs.length
       ) : Infinity;


   // list :: StringOrArrayLike b => b -> [a]
   const list = xs =>
       // xs itself, if it is an Array,
       // or an Array derived from xs.
       Array.isArray(xs) ? (
           xs
       ) : Array.from(xs || []);


   // ord :: Char -> Int
   const ord = c =>
       // Unicode ordinal value of the character.
       c.codePointAt(0);


   // quoted :: Char -> String -> String
   const quoted = c =>
       // A string flanked on both sides
       // by a specified quote character.
       s => c + s + c;


   // take :: Int -> [a] -> [a]
   // take :: Int -> String -> String
   const take = n =>
       // The first n elements of a list,
       // string of characters, or stream.
       xs => 'GeneratorFunction' !== xs
       .constructor.constructor.name ? (
           xs.slice(0, n)
       ) : [].concat.apply([], Array.from({
           length: n
       }, () => {
           const x = xs.next();
           return x.done ? [] : [x.value];
       }));


   // zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]
   const zipWith = f =>
       // A map of f over each stepwise pair in 
       // xs and ys, up to the length of the shorter
       // of those lists.
       xs => ys => {
           const
               n = Math.min(length(xs), length(ys)),
               vs = take(n)(list(ys));
           return take(n)(list(xs))
               .map((x, i) => f(x)(vs[i]));
       };

   // MAIN ---
   return main()

})();</lang>

Output:

First inconsistent character:

         '' (0 chars) -> None
      '   ' (3 chars) -> None
        '2' (1 chars) -> None
      '333' (3 chars) -> None
      '.55' (3 chars) -> '5' at index 1 (0x35)
   'tttTTT' (6 chars) -> 'T' at index 3 (0x54)
'4444 444k' (9 chars) -> ' ' at index 4 (0x20)
 '🐶🐶🐺🐶' (4 chars) -> '🐺' at index 2 (0x1f43a)
 '🎄🎄🎄🎄' (4 chars) -> None

jq

jq's "index origin" is 0. The hexadecimal encodings can be computed using the jq code at Non-decimal_radices/Convert#jq.

<lang sh>jq -rn '

 def firstdifferent:
   label $out
   | foreach explode[] as $i ({index:-1};
       .prev = .i | .i = $i | .index +=1;
       if .prev and $i != .prev then .index, break $out else empty end)
     // null ;
 
 def lpad($n): " "*($n-length) + "\"\(.)\"" ;
 
 [" "*10, "length", "same", "index", "char"],
 (inputs
  | firstdifferent as $d
  | [lpad(10), length, ($d == null)] + (if $d then [$d, .[$d:$d+1]] else null end) )
 | @tsv

'</lang>

Output:

Using as input the (JSON) strings shown in the first column of the output as shown below, the output is: <lang sh>

         	length	same	index	char
         ""	0	true
      "   "	3	true
        "2"	1	true
      "333"	3	true
      ".55"	3	false	1	5
   "tttTTT"	6	false	3	T
"4444 444k"	9	false	4	 
"🐶🐶🐺🐶"	4	false	2	🐺
"🎄🎄🎄🎄"	4	true</lang>

Julia

<lang julia>firstdifferent(s) = isempty(s) ? nothing : findfirst(x -> x != s[1], s)

function testfunction(strings)

  println("String                  | Length | All Same | First Different(Hex) | Position\n" *
          "-----------------------------------------------------------------------------")
   for s in strings
       n = firstdifferent(s)
       println(rpad(s, 27), rpad(length(s), 9), n == nothing ? "yes" :
           rpad("no               $(s[n])   ($(string(Int(s[n]), base=16)))", 36) * string(n))
   end

end

testfunction([ "", " ", "2", "333",

   ".55",
   "tttTTT",
   "4444 444k",
   "pépé",
   "🐶🐶🐺🐶",
   "🎄🎄🎄🎄",

])

</lang>

Output:

String                  | Length | All Same | First Different(Hex) | Position
-----------------------------------------------------------------------------
                           0        yes
                           3        yes
2                          1        yes
333                        3        yes
.55                        3        no               5   (35)           2
tttTTT                     6        no               T   (54)           4
4444 444k                  9        no                   (20)           5
pépé                       4        no               é   (e9)           2
🐶🐶🐺🐶                 4        no               🐺  (1f43a)        9
🎄🎄🎄🎄                   4        yes

Kotlin

Translation of: Go

<lang scala>fun analyze(s: String) {

   println("Examining [$s] which has a length of ${s.length}:")
   if (s.length > 1) {
       val b = s[0]
       for ((i, c) in s.withIndex()) {
           if (c != b) {
               println("    Not all characters in the string are the same.")
               println("    '$c' (0x${Integer.toHexString(c.toInt())}) is different at position $i")
               return
           }
       }
   }
   println("    All characters in the string are the same.")

}

fun main() {

   val strs = listOf("", "   ", "2", "333", ".55", "tttTTT", "4444 444k")
   for (str in strs) {
       analyze(str)
   }

}</lang>

Output:

Examining [] which has a length of 0:
    All characters in the string are the same.
Examining [   ] which has a length of 3:
    All characters in the string are the same.
Examining [2] which has a length of 1:
    All characters in the string are the same.
Examining [333] which has a length of 3:
    All characters in the string are the same.
Examining [.55] which has a length of 3:
    Not all characters in the string are the same.
    '5' (0x35) is different at position 1
Examining [tttTTT] which has a length of 6:
    Not all characters in the string are the same.
    'T' (0x54) is different at position 3
Examining [4444 444k] which has a length of 9:
    Not all characters in the string are the same.
    ' ' (0x20) is different at position 4

Lambdatalk

<lang scheme> {def firstDifferingChar

{def firstDifferingChar.r
 {lambda {:w :i :n}
  {if {or {> :i :n} {= {+ :i 1} {W.length :w}}}
  then all characters are the same
  else {if {not {W.equal? {W.get :i :w} {W.get {+ :i 1} :w}}}
  then at position {+ :i 1} {W.get :i :w} becomes {W.get {+ :i 1} :w} 
  else {firstDifferingChar.r :w {+ :i 1} :n}}}}}
{lambda {:w}
 {if {= {W.length :w} 1}
  then :w is a single character
  else {firstDifferingChar.r :w 0 {W.length :w}}}}}

-> firstDifferingChar

{firstDifferingChar 2} -> 2 is a single character {firstDifferingChar 333} -> all characters are the same {firstDifferingChar .55} -> at position 1 . becomes 5 {firstDifferingChar tttTTT} -> at position 3 t becomes T </lang>

Lua

<lang lua>function analyze(s)

   print(string.format("Examining [%s] which has a length of %d:", s, string.len(s)))
   if string.len(s) > 1 then
       local last = string.byte(string.sub(s,1,1))
       for i=1,string.len(s) do
           local c = string.byte(string.sub(s,i,i))
           if last ~= c then
               print("    Not all characters in the string are the same.")
               print(string.format("    '%s' (0x%x) is different at position %d", string.sub(s,i,i), c, i - 1))
               return
           end
       end
   end
   print("    All characters in the string are the same.")

end

function main()

   analyze("")
   analyze("   ")
   analyze("2")
   analyze("333")
   analyze(".55")
   analyze("tttTTT")
   analyze("4444 444k")

end

main()</lang>

Output:

Examining [] which has a length of 0:
    All characters in the string are the same.
Examining [   ] which has a length of 3:
    All characters in the string are the same.
Examining [2] which has a length of 1:
    All characters in the string are the same.
Examining [333] which has a length of 3:
    All characters in the string are the same.
Examining [.55] which has a length of 3:
    Not all characters in the string are the same.
    '5' (0x35) is different at position 1
Examining [tttTTT] which has a length of 6:
    Not all characters in the string are the same.
    'T' (0x54) is different at position 3
Examining [4444 444k] which has a length of 9:
    Not all characters in the string are the same.
    ' ' (0x20) is different at position 4

Maple

<lang Maple>CheckSame:=proc(s) local i, index; printf("input: \"%s\", length: %a\n", s, StringTools:-Length(s)); for i from 2 to StringTools:-Length(s) do if (s[i - 1] <> s[i]) then printf("The given string has different characters.\n"); printf("The first different character is %a (0x%x) which appears at index %a.\n\n", s[i], convert(s[i], 'bytes')[1], i); return; end if; end do; # if no difference found printf("The given string has all same characters.\n\n"); end proc:

Test

CheckSame(""); CheckSame(" "); CheckSame("2"); CheckSame("333"); CheckSame(".55"); CheckSame("tttTTT"); CheckSame("4444 444k");</lang>

Output:

input: "", length: 0
The given string has all same characters.

input: "   ", length: 3
The given string has all same characters.

input: "2", length: 1
The given string has all same characters.

input: "333", length: 3
The given string has all same characters.

input: ".55", length: 3
The given string has different characters.
The first different character is "5" (0x35) which appears at index 2.

input: "tttTTT", length: 6
The given string has different characters.
The first different character is "T" (0x54) which appears at index 4.

input: "4444 444k", length: 9
The given string has different characters.
The first different character is " " (0x20) which appears at index 5.

Mathematica / Wolfram Language

<lang Mathematica>ClearAll[AllSameCharacters] AllSameCharacters[s_String] := Module[{c = Characters[s], i = 0, tf},

 If[Length[c] > 1,
   tf = AllTrue[Rest[c], (i++; # == First[c]) &];
   If[tf,
    Print["input = \"", s, "\", Length = ", StringLength[s], 
     ", All the same!"]
    ,
    Print["input = \"", s, "\", Length = ", StringLength[s], 
     ", Character " <> ToString[i + 1] <> 
      " is different from character " <> ToString[i], ", hex = ", 
     IntegerString[First@ToCharacterCode[ci + 1], 16]]
    ]
   ,
   Print["input = \"", s, "\", Length = ", StringLength[s], 
    ", All the same!"]
   ];
 ]

AllSameCharacters[""] AllSameCharacters[" "] AllSameCharacters["2"] AllSameCharacters["333"] AllSameCharacters[".55"] AllSameCharacters["tttTTT"] AllSameCharacters["4444 444k"]</lang>

Output:

input = "", Length = 0, All the same!
input = "   ", Length = 3, All the same!
input = "2", Length = 1, All the same!
input = "333", Length = 3, All the same!
input = ".55", Length = 3, Character 2 is different from character 1, hex = 35
input = "tttTTT", Length = 6, Character 4 is different from character 3, hex = 54
input = "4444 444k", Length = 9, Character 5 is different from character 4, hex = 20

Nanoquery

Translation of: Java

<lang nanoquery>def analyze(s)

   s = str(s)
   println "Examining [" + s + "] which has a length of " + str(len(s)) + ":"

   if len(s) < 2
       println "\tAll characters in the string are the same."
       return
   end

   for i in range(0, len(s) - 2)
       if s[i] != s[i + 1]
           println "\tNot all characters in the string are the same."
           println "\t'" + s[i + 1] + "' " + format("(0x%x)", ord(s[i + 1])) +\
                   " is different at position " + str(i + 2)
           return
       end
   end

   println "\tAll characters in the string are the same."

end

tests = {"", " ", "2", "333", ".55", "tttTTT", "444 444k"} for s in tests

  analyze(s)

end</lang>

Output:

Examining [] which has a length of 0:
        All characters in the string are the same.
Examining [   ] which has a length of 3:
        All characters in the string are the same.
Examining [2] which has a length of 1:
        All characters in the string are the same.
Examining [333] which has a length of 3:
        All characters in the string are the same.
Examining [.55] which has a length of 3:
        Not all characters in the string are the same.
        '5' (0x35) is different at position 2
Examining [tttTTT] which has a length of 6:
        Not all characters in the string are the same.
        'T' (0x54) is different at position 4
Examining [444 444k] which has a length of 8:
        Not all characters in the string are the same.
        ' ' (0x20) is different at position 4

Nim

<lang nim>import strformat

proc analyze(str: string) =

   if str.len() > 1:
       var first = str[0]
       for i, c in str:
           if c != first:
               echo "'", str, "': [len: ", str.len(), "] not all characters are the same. starts to differ at index ",
                   i, ": '", first, "' != '", c, "' [", fmt"{ord(c):#x}", "]"
               return
   echo "'", str, "': [len: ", str.len(), "] all characters are the same"

var strings = @["", " ", "2", "333", ".55", "tttTTT", "4444 444k"] for str in strings:

   analyze(str)</lang>

Output:

'': [len: 0] all characters are the same
'   ': [len: 3] all characters are the same
'2': [len: 1] all characters are the same
'333': [len: 3] all characters are the same
'.55': [len: 3] not all characters are the same. starts to differ at index 1: '.' != '5' [0x35]
'tttTTT': [len: 6] not all characters are the same. starts to differ at index 3: 't' != 'T' [0x54]
'4444 444k': [len: 9] not all characters are the same. starts to differ at index 4: '4' != ' ' [0x20]

OCaml

Original version by User:Vanyamil <lang OCaml> (* Task: Determine if a string has all the same characters *)

(* Create a function that determines whether all characters in a string are identical,

   or returns the index of first different character.

   Using the option type here to combine the functionality.

)

let str_first_diff_char (s : string) : int option =

   let len = String.length s in
   if len = 0 
   then None
   else
   let first = s.[0] in
   let rec helper idx =
       if idx >= len 
       then None
       else if s.[idx] = first
       then helper (idx + 1)
       else Some idx
   in
   helper 1

(* Task display: using format of Ada

   Example:

Input = "333", length = 3

All characters are the same.

Input = ".55", length = 3

First difference at position 2, character = '5', hex = 16#35#

)

let format_answer s =

   let first_line = "Input = \"" ^ s ^ "\", length = " ^ (s |> String.length |> string_of_int) in
   let second_line = match str_first_diff_char s with
       | None -> " All characters are the same."
       | Some idx -> Printf.sprintf " First difference at position %d, character = %C, hex = %#x" (idx+1) s.[idx] (Char.code s.[idx])
   in
   print_endline first_line; print_endline second_line

let _ =

   [""; "   "; "2"; "333"; ".55"; "tttTTT"; "4444 444k"]
   |> List.iter format_answer

</lang>

Output:

Input = "", length = 0
 All characters are the same.
Input = "   ", length = 3
 All characters are the same.
Input = "2", length = 1
 All characters are the same.
Input = "333", length = 3
 All characters are the same.
Input = ".55", length = 3
 First difference at position 2, character = '5', hex = 0x35
Input = "tttTTT", length = 6
 First difference at position 4, character = 'T', hex = 0x54
Input = "4444 444k", length = 9
 First difference at position 5, character = ' ', hex = 0x20

Pascal

<lang pascal>program SameNessOfChar; {$IFDEF FPC}

  {$MODE DELPHI}{$OPTIMIZATION ON,ALL}{$CODEALIGN proc=16}{$ALIGN 16}

{$ELSE}

 {$APPTYPE CONSOLE}

{$ENDIF} uses

 sysutils;//Format

const

 TestData : array[0..6] of String =
    (,'   ','2','333','.55','tttTTT','4444 444k');

function PosOfDifferentChar(const s: String):NativeInt; var

 i: Nativeint;
 ch:char;

Begin

 result := length(s);
 IF result < 2 then
   EXIT;
 ch := s[1];
 i := 2;
 while (i< result) AND (S[i] =ch) do
   inc(i);
 result := i;

end;

procedure OutIsAllSame(const s: String); var

 l,len: NativeInt;

Begin

 l := PosOfDifferentChar(s);
 len := Length(s);
 write('"',s,'" of length ',len);
 IF l = len then
   writeln(' contains all the same character')
 else
   writeln(Format(' is different at position %d "%s" (0x%X)',[l,s[l],Ord(s[l])]));

end;

var

 i : NativeInt;

begin

 For i := Low(TestData) to HIgh(TestData) do
   OutIsAllSame(TestData[i]);

end.</lang>

Output:

"" of length 0 contains all the same character
"   " of length 3 contains all the same character
"2" of length 1 contains all the same character
"333" of length 3 contains all the same character
".55" of length 3 is different at position 2 "5" (0x35)
"tttTTT" of length 6 is different at position 4 "T" (0x54)
"4444 444k" of length 9 is different at position 5 " " (0x20)

Perl

<lang perl>use strict; use warnings; use feature 'say'; use utf8; binmode(STDOUT, ':utf8'); use List::AllUtils qw(uniq); use Unicode::UCD 'charinfo'; use Unicode::Normalize qw(NFC);

for my $str (

   ,
   '   ',
   '2',
   '333',
   '.55',
   'tttTTT',
   '4444 444k',
   'Δ👍👨',
   '🇬🇧🇬🇧🇬🇧🇬🇧',
   "\N{LATIN CAPITAL LETTER A}\N{COMBINING DIAERESIS}\N{COMBINING MACRON}" .
   "\N{LATIN CAPITAL LETTER A WITH DIAERESIS}\N{COMBINING MACRON}" .
   "\N{LATIN CAPITAL LETTER A WITH DIAERESIS AND MACRON}"

) {

   my @S;
   push @S, NFC $1 while $str =~ /(\X)/g;
   printf qq{\n"$str" (length: %d) has }, scalar @S;
   my @U = uniq @S;
   if (1 != @U and @U > 0) {
       say 'different characters:';
       for my $l (@U) {
           printf "'%s' %s (0x%x) in positions: %s\n",
               $l, charinfo(ord $l)->{'name'}, ord($l), join ', ', map { 1+$_ } grep { $l eq $S[$_] } 0..$#S;
       }
   } else {
       say 'the same character in all positions.'
   }

}</lang>

Output:

"" (length: 0) has the same character in all positions.

"   " (length: 3) has the same character in all positions.

"2" (length: 1) has the same character in all positions.

"333" (length: 3) has the same character in all positions.

".55" (length: 3) has different characters:
'.' FULL STOP (0x2e) in positions: 1
'5' DIGIT FIVE (0x35) in positions: 2, 3

"tttTTT" (length: 6) has different characters:
't' LATIN SMALL LETTER T (0x74) in positions: 1, 2, 3
'T' LATIN CAPITAL LETTER T (0x54) in positions: 4, 5, 6

"4444 444k" (length: 9) has different characters:
'4' DIGIT FOUR (0x34) in positions: 1, 2, 3, 4, 6, 7, 8
' ' SPACE (0x20) in positions: 5
'k' LATIN SMALL LETTER K (0x6b) in positions: 9

"Δ👍👨" (length: 3) has different characters:
'Δ' GREEK CAPITAL LETTER DELTA (0x394) in positions: 1
'👍' THUMBS UP SIGN (0x1f44d) in positions: 2
'👨' MAN (0x1f468) in positions: 3

"🇬🇧🇬🇧🇬🇧🇬🇧" (length: 4) has the same character in all positions.

"ǞǞǞ" (length: 3) has the same character in all positions.

Phix

<lang Phix>procedure samechar(sequence s)

   string msg = "all characters are the same"
   integer l = length(s)
   if l>=2 then
       integer ch = s[1]
       for i=2 to l do
           integer si = s[i]
           if si!=ch then
               msg = sprintf(`first different character "%c"(#%02x) at position %d`,{si,si,i})
               exit
           end if
       end for
   end if
   printf(1,"\"%s\" (length %d): %s\n",{s,l,msg})

end procedure

constant tests = {""," ","2","333",".55","tttTTT","4444 444k",

                 utf8_to_utf32("🐶🐶🐺🐶"),utf8_to_utf32("🎄🎄🎄🎄")}

for i=1 to length(tests) do samechar(tests[i]) end for</lang>

Output:

"" (length 0): all characters are the same
"   " (length 3): all characters are the same
"2" (length 1): all characters are the same
"333" (length 3): all characters are the same
".55" (length 3): first different character "5"(#35) at position 2
"tttTTT" (length 6): first different character "T"(#54) at position 4
"4444 444k" (length 9): first different character " "(#20) at position 5
"🐶🐶🐺🐶" (length 4): first different character "🐺"(#1F43A) at position 3
"🎄🎄🎄🎄" (length 4): all characters are the same

PicoLisp

<lang PicoLisp>(de equal? (Str)

  (let (Lst (chop Str)  C (car Lst)  P 2  F)
     (prin Str ": ")
     (for A (cdr Lst)
        (NIL (= A C) (on F) (prin "First different character " A))
        (inc 'P) )
     (if F (prinl " at position: " P) (prinl "all characters are the same")) ) )

(equal?) (equal? " ") (equal? "333") (equal? ".55") (equal? "tttTTT")</lang>

Output:

: all characters are the same
   : all characters are the same
333: all characters are the same
.55: First different character 5 at position: 2
tttTTT: First different character T at position: 4

Plain English

<lang plainenglish>To run: Start up. Show the uniformity of "". Show the uniformity of " ". Show the uniformity of "2". Show the uniformity of "333". Show the uniformity of ".55". Show the uniformity of "tttTTT". Show the uniformity of "4444 444k". Wait for the escape key. Shut down.

To find the first different character in a string giving a byte and a count: If the string is blank, put -1 into the count; exit. Put the string's first's target into a first letter. Slap a substring on the string. Loop. If a counter is past the string's length, put -1 into the count; exit. Put the substring's first's target into a letter. If the letter is not the first letter, put the letter into the byte; put the counter minus 1 into the count; exit. Add 1 to the substring's first. Repeat.

To show the uniformity of a string: Write """" then the string then """ (length " then the string's length then ") " on the console without advancing. Find the first different character in the string giving a byte and a count. If the count is -1, write "contains all the same character." on the console; exit. Convert the byte to a nibble string. Write "contains a different character at index " then the count then ": '" then the byte then "' (0x" then the nibble string then ")." on the console.</lang>

Output:

"" (length 0) contains all the same character.
"   " (length 3) contains all the same character.
"2" (length 1) contains all the same character.
"333" (length 3) contains all the same character.
".55" (length 3) contains a different character at index 1: '5' (0x35).
"tttTTT" (length 6) contains a different character at index 3: 'T' (0x54).
"4444 444k" (length 9) contains a different character at index 4: ' ' (0x20).

Prolog

Works with: SWI-Prolog version 7

- system:set_prolog_flag(double_quotes,chars) .

main

-

same_or_different("") , same_or_different(" ") , same_or_different("2") , same_or_different("333") , same_or_different(".55") , same_or_different("tttTTT") , same_or_different("4444 444k") .

%! same_or_different(INPUTz0)

same_or_different(INPUTz0)

-

system:format('input string is "~s" .~n',[INPUTz0]) , examine(INPUTz0) .

%! examine(INPUTz0)

examine([])

-

! , system:format('all the same characters .~n',[]) .

examine([COMPARE0|INPUTz0])

-

examine(INPUTz0,COMPARE0,2,_INDEX_) .

%! examine(INPUTz0,COMPARE0,INDEX0,INDEX)

examine([],_COMPARE0_,INDEX0,INDEX0)

-

! , system:format('all the same characters .~n',[]) .

examine([COMPARE0|INPUTz0],COMPARE0,INDEX0,INDEX)

-

! , INDEX1 is INDEX0 + 1 , examine(INPUTz0,COMPARE0,INDEX1,INDEX) .

examine([DIFFERENT0|_INPUTz0_],COMPARE0,INDEX0,INDEX0)

-

prolog:char_code(DIFFERENT0,DIFFERENT_CODE) , system:format('character "~s" (hex ~16r) different than "~s" at 1-based index ~10r .~n',[[DIFFERENT0],DIFFERENT_CODE,[COMPARE0],INDEX0]) .

</lang>

Output:

/*
?- main .
input string is "" .
all the same characters .
input string is "   " .
all the same characters .
input string is "2" .
all the same characters .
input string is "333" .
all the same characters .
input string is ".55" .
character "5" (hex 35) different than "." at 1-based index 2 .
input string is "tttTTT" .
character "T" (hex 54) different than "t" at 1-based index 4 .
input string is "4444 444k" .
character " " (hex 20) different than "4" at 1-based index 5 .
true.

?- 
*/

Python

Functional

What we are testing here is the cardinality of the set of characters from which a string is drawn, so the first thought might well be to use set.

On the other hand, itertools.groupby has the advantage of yielding richer information (the list of groups is ordered), for less work.

Works with: Python version 3.7

<lang python>Determine if a string has all the same characters

from itertools import groupby

firstDifferingCharLR :: String -> Either String Dict

def firstDifferingCharLR(s):

   Either a message reporting that no character changes were
      seen, or a dictionary with details of the  first character
      (if any) that differs from that at the head of the string.
   
   def details(xs):
       c = xs[1][0]
       return {
           'char': repr(c),
           'hex': hex(ord(c)),
           'index': s.index(c),
           'total': len(s)
       }
   xs = list(groupby(s))
   return Right(details(xs)) if 1 < len(xs) else (
       Left('Total length ' + str(len(s)) + ' - No character changes.')
   )

TEST ----------------------------------------------------
main :: IO ()

def main():

   Test of 7 strings

   print(fTable('First, if any, points of difference:\n')(repr)(
       either(identity)(
           lambda dct: dct['char'] + ' (' + dct['hex'] +
           ') at character ' + str(1 + dct['index']) +
           ' of ' + str(dct['total']) + '.'
       )
   )(firstDifferingCharLR)([
       ,
       '   ',
       '2',
       '333',
       '.55',
       'tttTTT',
       '4444 444'
   ]))

GENERIC -------------------------------------------------

either :: (a -> c) -> (b -> c) -> Either a b -> c

def either(fl):

   The application of fl to e if e is a Left value,
      or the application of fr to e if e is a Right value.
   
   return lambda fr: lambda e: fl(e['Left']) if (
       None is e['Right']
   ) else fr(e['Right'])

identity :: a -> a

def identity(x):

   The identity function.
   return x

fTable :: String -> (a -> String) ->
(b -> String) -> (a -> b) -> [a] -> String

def fTable(s):

   Heading -> x display function -> fx display function ->
      f -> xs -> tabular string.
   
   def go(xShow, fxShow, f, xs):
       ys = [xShow(x) for x in xs]
       w = max(map(len, ys))
       return s + '\n' + '\n'.join(map(
           lambda x, y: y.rjust(w, ' ') + ' -> ' + fxShow(f(x)),
           xs, ys
       ))
   return lambda xShow: lambda fxShow: lambda f: lambda xs: go(
       xShow, fxShow, f, xs
   )

Left :: a -> Either a b

def Left(x):

   Constructor for an empty Either (option type) value
      with an associated string.
   
   return {'type': 'Either', 'Right': None, 'Left': x}

Right :: b -> Either a b

def Right(x):

   Constructor for a populated Either (option type) value
   return {'type': 'Either', 'Left': None, 'Right': x}

MAIN ---

if __name__ == '__main__':

   main()</lang>

Output:

First, if any, points of difference:

        '' -> Total length 0 - No character changes.
     '   ' -> Total length 3 - No character changes.
       '2' -> Total length 1 - No character changes.
     '333' -> Total length 3 - No character changes.
     '.55' -> '5' (0x35) at character 2 of 3.
  'tttTTT' -> 'T' (0x54) at character 4 of 6.
'4444 444' -> ' ' (0x20) at character 5 of 8.

and for very long strings, itertools.takewhile (here used in the definition of a more general span function), should be slightly more efficient:

<lang python>Determine if a string has all the same characters

from itertools import takewhile

inconsistentChar :: String -> Maybe (Int, Char)

def inconsistentChar(s):

   Just the first inconsistent character and its position,
      or Nothing if all the characters of s are the same,
   
   if s:
       h = s[0]
       pre, post = span(lambda c: h == c)(s)
       return Just((len(pre), post[0])) if post else Nothing()
   else:
       return Nothing()

--------------------------TEST---------------------------
main :: IO ()

def main():

   Consistency tests of seven strings

   samples = [, '   ', '2', '333', '.55', 'tttTTT', '4444 444']
   w = 1 + max(map(len, samples))

   def pfx(s):
       return ("'" + s).rjust(w) + "' -> "

   def charPosn(ic):
       i, c = ic
       return "inconsistent '" + c + "' (" + hex(ord(c)) + ")" + (
           " at char " + str(1 + i)
       )

   print(main.__doc__ + ':\n')
   print(
       '\n'.join([
           pfx(s) + maybe('consistent')(charPosn)(
               inconsistentChar(s)
           )
           for s in samples
       ])
   )

-------------------------GENERIC-------------------------

Just :: a -> Maybe a

def Just(x):

   Constructor for an inhabited Maybe (option type) value.
      Wrapper containing the result of a computation.
   
   return {'type': 'Maybe', 'Nothing': False, 'Just': x}

Nothing :: Maybe a

def Nothing():

   Constructor for an empty Maybe (option type) value.
      Empty wrapper returned where a computation is not possible.
   
   return {'type': 'Maybe', 'Nothing': True}

maybe :: b -> (a -> b) -> Maybe a -> b

def maybe(v):

   Either the default value v, if m is Nothing,
      or the application of f to x,
      where m is Just(x).
   
   return lambda f: lambda m: v if None is m or m.get('Nothing') else (
       f(m.get('Just'))
   )

span :: (a -> Bool) -> [a] -> ([a], [a])

def span(p):

   The longest (possibly empty) prefix of xs
      that contains only elements satisfying p,
      tupled with the remainder of xs.
      span p xs is equivalent to (takeWhile p xs, dropWhile p xs).
   
   def go(xs):
       prefix = list(takewhile(p, xs))
       return (prefix, xs[len(prefix):])
   return lambda xs: go(xs)

MAIN ---

if __name__ == '__main__':

   main()</lang>

Putting itertools aside, we could equivalently define inconsistentChar as:

<lang python># inconsistentChar :: String -> Maybe (Int, Char) def inconsistentChar(s):

   Just the first inconsistent character and its index,
      or Nothing if all the characters of s are the same.
   
   return next(
       (Just(ix) for ix in enumerate(s) if s[0] != ix[1]),
       Nothing()
   )</lang>

Output:

Consistency tests of seven strings:

        '' -> consistent
     '   ' -> consistent
       '2' -> consistent
     '333' -> consistent
     '.55' -> inconsistent '5' (0x35) at char 2
  'tttTTT' -> inconsistent 'T' (0x54) at char 4
'4444 444' -> inconsistent ' ' (0x20) at char 5

Quackery

 [ 0 swap
   dup size 0 = iff 
     drop done 
   behead swap witheach
     [ over != if
         [ drop i^ 1+
           swap conclude ] ]
   drop ]                    is allsame ( [ --> n )

 ( 0 indicates all items are the same,
   otherwise n is first different item )

 [ say ' String: "' dup echo$
   say '" length ' dup size echo  
   dup allsame dup 0 = iff
     [ say ', all characters are the same.'
       2drop ]
   else
     [ say ', first difference is item '
       dup echo 
       say ', char "' 
       peek dup emit
       say '", hex: '
       16 base put echo base release
       say '.' ]
   cr ]                      is task    ( $ -->   )

 $ ""          task
 $ "   "       task
 $ "2"         task
 $ ".55"       task
 $ "tttTTT"    task
 $ "4444 444k" task</lang>

Output:

 String: "" length 0, all characters are the same.
 String: "   " length 3, all characters are the same.
 String: "2" length 1, all characters are the same.
 String: ".55" length 3, first difference is item 1, char "5", hex: 35.
 String: "tttTTT" length 6, first difference is item 3, char "T", hex: 54.
 String: "4444 444k" length 9, first difference is item 4, char " ", hex: 20.

R

<lang r>isAllSame<-function(string) {

 strLength<-nchar(string)
 if(length(strLength)>1)
 {
   #R has a distinction between the length of a string and that of a character vector. It is a common source
   #of problems when coming from another language. We will try to avoid the topic here.
   #For our purposes, let us only say that there is a good reason why we have made
   #isAllSame(c("foo", "bar") immediately throw an error.
   stop("This task is intended for character vectors with lengths of at most 1.")
 }
 else if(length(strLength)==0)
 {
   cat("Examining a character vector of length 0.\n")
   TRUE
 }
 else if(strLength==0)
 {
   cat("Examining a character vector of length 1, containing an empty string.\n")
   TRUE
 }
 else
 {
   cat("Examining the string", paste0(sQuote(string), ","),
       "which is of length", paste0(strLength, ":"), "\n")
   #strsplit outputs a list. Its first element is the vector of characters that we desire.
   characters<-strsplit(string, "")1
   #Our use of match is using R's vector recycling rules. Every element is being checked
   #against the first.
   differentElementIndex<-match(FALSE, characters[1]==characters, nomatch = 0)
   if(differentElementIndex==0)
   {
     cat("It has no duplicates.\n")
     TRUE
   }
   else
   {
     cat("It has duplicates. ")
     firstDifferentCharacter<-characters[differentElementIndex]
     cat(sQuote(firstDifferentCharacter), "is the first different character. It has hex value",
         sprintf("0x%X", as.integer(charToRaw(firstDifferentCharacter))),
         "and is at index", paste0(differentElementIndex, "."), "\n")
     FALSE
   }
 }

}

Tests:

cat("Test: A string of length 0 (an empty string):\n") cat("Test 1 of 2: An empty character vector:\n") print(isAllSame(character(0))) cat("Test 2 of 2: A character vector containing the empty string:\n") print(isAllSame("")) cat("Test: A string of length 3 which contains three blanks:\n") print(isAllSame(" ")) cat("Test: A string of length 1 which contains 2:\n") print(isAllSame("2")) cat("Test: A string of length 3 which contains 333:\n") print(isAllSame("333")) cat("Test: A string of length 3 which contains .55:\n") print(isAllSame(".55")) cat("Test: A string of length 6 which contains tttTTT:\n") print(isAllSame("tttTTT")) cat("Test: A string of length 9 which contains 4444 444k:\n") print(isAllSame("4444 444k"))</lang>

Output:

Test: A string of length 0 (an empty string):
Test 1 of 2: An empty character vector:
Examining a character vector of length 0.
[1] TRUE
Test 2 of 2: A character vector containing the empty string:
Examining a character vector of length 1, containing an empty string.
[1] TRUE
Test: A string of length 3 which contains three blanks:
Examining the string ‘   ’, which is of length 3: 
It has no duplicates.
[1] TRUE
Test: A string of length 1 which contains 2:
Examining the string ‘2’, which is of length 1: 
It has no duplicates.
[1] TRUE
Test: A string of length 3 which contains 333:
Examining the string ‘333’, which is of length 3: 
It has no duplicates.
[1] TRUE
Test: A string of length 3 which contains .55:
Examining the string ‘.55’, which is of length 3: 
It has duplicates. ‘5’ is the first different character. It has hex value 0x35 and is at index 2. 
[1] FALSE
Test: A string of length 6 which contains tttTTT:
Examining the string ‘tttTTT’, which is of length 6: 
It has duplicates. ‘T’ is the first different character. It has hex value 0x54 and is at index 4. 
[1] FALSE
Test: A string of length 9 which contains 4444 444k:
Examining the string ‘4444 444k’, which is of length 9: 
It has duplicates. ‘ ’ is the first different character. It has hex value 0x20 and is at index 5. 
[1] FALSE

Racket

<lang racket>#lang racket

(define (first-non-matching-index l =)

 (and (not (null? l)) (index-where l (curry (negate =) (car l)))))

(define (report-string-sameness s)

 (printf "~s (length: ~a): ~a~%"
         s
         (string-length s)
         (cond [(first-non-matching-index (string->list s) char=?)
                => (λ (i)
                     (let ((c (string-ref s i)))
                       (format "first different character ~s(~a) at position: ~a" c (char->integer c) (add1 i))))]
               [else "all characters are the same"])))

(module+ test

 (for-each report-string-sameness '("" "   " "2" "333" ".55" "tttTTT" "4444 444k")))</lang>

Output:

"" (length: 0): all characters are the same
"   " (length: 3): all characters are the same
"2" (length: 1): all characters are the same
"333" (length: 3): all characters are the same
".55" (length: 3): first different character #\5(53) at position: 2
"tttTTT" (length: 6): first different character #\T(84) at position: 4
"4444 444k" (length: 9): first different character #\space(32) at position: 5

Raku

(formerly Perl 6)

Works with: Rakudo version 2020.08.1

The last string demonstrates how Raku can recognize that glyphs made up of different combinations of combining characters can compare the same. It is built up from explicit codepoints to show that each of the glyphs is made up of different combinations.

<lang perl6> -> $str {

   my $i = 0;
   print "\n{$str.raku} (length: {$str.chars}), has ";
   my %m;
   %m{$_}.push: ++$i for $str.comb;

   if %m > 1 {
       say "different characters:";
       say "'{.key}' ({.key.uninames}; hex ordinal: {(.key.ords).fmt: "0x%X"})" ~
       " in positions: {.value.join: ', '}" for %m.sort( *.value[0] );
   } else {
       say "the same character in all positions."
   }

} for

   ,
   '   ',
   '2',
   '333',
   '.55',
   'tttTTT',
   '4444 444k',
   '🇬🇧🇬🇧🇬🇧🇬🇧',
   "\c[LATIN CAPITAL LETTER A]\c[COMBINING DIAERESIS]\c[COMBINING MACRON]" ~
   "\c[LATIN CAPITAL LETTER A WITH DIAERESIS]\c[COMBINING MACRON]" ~
   "\c[LATIN CAPITAL LETTER A WITH DIAERESIS AND MACRON]",
   'AАΑꓮ𐌀𐊠Ꭺ'</lang>

Output:

"" (length: 0), has the same character in all positions.

"   " (length: 3), has the same character in all positions.

"2" (length: 1), has the same character in all positions.

"333" (length: 3), has the same character in all positions.

".55" (length: 3), has different characters:
'.' (FULL STOP; hex ordinal: 0x2E) in positions: 1
'5' (DIGIT FIVE; hex ordinal: 0x35) in positions: 2, 3

"tttTTT" (length: 6), has different characters:
't' (LATIN SMALL LETTER T; hex ordinal: 0x74) in positions: 1, 2, 3
'T' (LATIN CAPITAL LETTER T; hex ordinal: 0x54) in positions: 4, 5, 6

"4444 444k" (length: 9), has different characters:
'4' (DIGIT FOUR; hex ordinal: 0x34) in positions: 1, 2, 3, 4, 6, 7, 8
' ' (SPACE; hex ordinal: 0x20) in positions: 5
'k' (LATIN SMALL LETTER K; hex ordinal: 0x6B) in positions: 9

"🇬🇧🇬🇧🇬🇧🇬🇧" (length: 4), has the same character in all positions.

"ǞǞǞ" (length: 3), has the same character in all positions.

"AАΑꓮ𐌀𐊠Ꭺ" (length: 7), has different characters:
'A' (LATIN CAPITAL LETTER A; hex ordinal: 0x41) in positions: 1
'А' (CYRILLIC CAPITAL LETTER A; hex ordinal: 0x410) in positions: 2
'Α' (GREEK CAPITAL LETTER ALPHA; hex ordinal: 0x391) in positions: 3
'ꓮ' (LISU LETTER A; hex ordinal: 0xA4EE) in positions: 4
'𐌀' (OLD ITALIC LETTER A; hex ordinal: 0x10300) in positions: 5
'𐊠' (CARIAN LETTER A; hex ordinal: 0x102A0) in positions: 6
'Ꭺ' (CHEROKEE LETTER GO; hex ordinal: 0x13AA) in positions: 7

REXX

<lang rexx>/*REXX program verifies that all characters in a string are all the same (character). */ @chr= ' [character' /* define a literal used for SAY.*/ @all= 'all the same character for string (length' /* " " " " " " */ @.= /*define a default for the @. array. */ parse arg x /*obtain optional argument from the CL.*/ if x\= then @.1= x /*if user specified an arg, use that. */

         else do;   @.1=                        /*use this null string if no arg given.*/
                    @.2= '   '                  /* "    "          "    "  "  "    "   */
                    @.3= 2                      /* "    "          "    "  "  "    "   */
                    @.4= 333                    /* "    "          "    "  "  "    "   */
                    @.5= .55                    /* "    "          "    "  "  "    "   */
                    @.6= 'tttTTT'               /* "    "          "    "  "  "    "   */
                    @.7= 4444 444k              /* "    "          "    "  "  "    "   */
              end                               /* [↑]  seventh value contains a blank.*/

    do j=1;    L= length(@.j)                   /*obtain the length of an array element*/
    if j>1  &  L==0     then leave              /*if arg is null and  J>1, then leave. */
    r= allSame(@.j)                             /*R:  ≡0,  or the location of bad char.*/
    if r\==0  then ?= substr(@.j,r,1)           /*if  not  monolithic, obtain the char.*/
    if r==0   then say '   ' @all L"):"  @.j
              else say 'not' @all L"):"  @.j  @chr ?  "('"c2x(?)"'x)  at position"  r"]."
    end   /*j*/

exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ allSame: procedure; parse arg y /*get a value from the argument list. */

        if y==  then return 0                 /*if  Y  is null,  then return 0 (zero)*/
        return verify(y, left(y,1) )            /*All chars the same?   Return 0 (zero)*/
                                                /*                else  return location*/</lang>

output when using the internal default inputs:

    all the same character for string (length 0):
    all the same character for string (length 3):
    all the same character for string (length 1): 2
    all the same character for string (length 3): 333
not all the same character for string (length 3): .55      [character 5 ('35'x)  at position 2].
not all the same character for string (length 6): tttTTT      [character T ('54'x)  at position 4].
not all the same character for string (length 9): 4444 444K      [character   ('20'x)  at position 5].

Ring

<lang ring> nputStr = [""," ","2","333",".55","tttTTT","4444 444k"]

for word in inputStr

   for x = 1 to len(word)
       for y = x + 1 to len(word)
           if word[x] != word[y]
              char = word[y]
              ? "Input = " + "'" + word + "'" + ", length = " + len(word)
              ? " First difference at position " + y + ", character = " + "'" + char + "'"
              loop 3
           ok
       next
   next

   ? "Input = " + "'" + word + "'" + ", length = " + len(word)
   ? "  All characters are the same."

next </lang>

Output:

Input = '', length = 0
  All characters are the same.
Input = '   ', length = 3
  All characters are the same.
Input = '2', length = 1
  All characters are the same.
Input = '333', length = 3
  All characters are the same.
Input = '.55', length = 3
 First difference at position 2, character = '5'
Input = 'tttTTT', length = 6
 First difference at position 4, character = 'T'
Input = '4444 444k', length = 9
 First difference at position 5, character = ' '

Ruby

<lang ruby>strings = ["", " ", "2", "333", ".55", "tttTTT", "4444 444k", "pépé", "🐶🐶🐺🐶", "🎄🎄🎄🎄"]

strings.each do |str|

 pos = str.empty? ? nil : str =~ /[^#{str[0]}]/
 print "#{str.inspect}  (size #{str.size}): "
 puts pos ? "first different char #{str[pos].inspect} (#{'%#x' % str[pos].ord}) at position #{pos}." : "all the same."

end </lang>

Output:

""  (size 0): all the same.
"   "  (size 3): all the same.
"2"  (size 1): all the same.
"333"  (size 3): all the same.
".55"  (size 3): first different char "5" (0x35) at position 1.
"tttTTT"  (size 6): first different char "T" (0x54) at position 3.
"4444   444k"  (size 11): first different char " " (0x20) at position 4.
"pépé"  (size 4): first different char "é" (0xe9) at position 1.
"🐶🐶🐺🐶"  (size 4): first different char "🐺" (0x1f43a) at position 2.
"🎄🎄🎄🎄"  (size 4): all the same.

Rust

<lang rust>fn test_string(input: &str) {

   println!("Checking string {:?} of length {}:", input, input.chars().count());

   let mut chars = input.chars();

   match chars.next() {
       Some(first) => {
           if let Some((character, pos)) = chars.zip(2..).filter(|(c, _)| *c != first).next() {
               println!("\tNot all characters are the same.");
               println!("\t{:?} (0x{:X}) at position {} differs.", character, character as u32, pos);

               return;
           }
       },
       None => {}
   }

   println!("\tAll characters in the string are the same");

}

fn main() {

   let tests = ["", "   ", "2", "333", ".55", "tttTTT", "4444 444k", "pépé", "🐶🐶🐺🐶", "🎄🎄🎄🎄"];

   for string in &tests {
       test_string(string);
   }

}</lang>

Output:

Checking string "" of length 0:
        All characters in the string are the same
Checking string "   " of length 3:
        All characters in the string are the same
Checking string "2" of length 1:
        All characters in the string are the same
Checking string "333" of length 3:
        All characters in the string are the same
Checking string ".55" of length 3:
        Not all characters are the same.
        '5' (0x35) at position 2 differs.
Checking string "tttTTT" of length 6:
        Not all characters are the same.
        'T' (0x54) at position 4 differs.
Checking string "4444 444k" of length 9:
        Not all characters are the same.
        ' ' (0x20) at position 5 differs.
Checking string "pépé" of length 4:
        Not all characters are the same.
        'é' (0xE9) at position 2 differs.
Checking string "🐶🐶🐺🐶" of length 4:
        Not all characters are the same.
        '🐺' (0x1F43A) at position 3 differs.
Checking string "🎄🎄🎄🎄" of length 4:
        All characters in the string are the same

Scala

<lang scala>import scala.collection.immutable.ListMap

object StringAllSameCharacters {

 /**Transform an input String into an HashMap of its characters and its first occurrence index*/
 def countChar( s : String) : Map[Char, Int] = {
   val mapChar = s.toSeq.groupBy(identity).map{ case (a,b) => a->s.indexOf(a) }
   val orderedMapChar = ListMap(mapChar.toSeq.sortWith(_._2 < _._2):_*)
   orderedMapChar
 }

 /**Check if all the characters of a String are the same given an input Hashmap of it */
 def areAllCharEquals ( mapChar : Map[Char, Int] ) : Boolean = {
   return mapChar.size <= 1
 }

 /**Retrieve the first "breaking" different character of a String*/
 def findFirstDifferentChar ( mapChar : Map[Char, Int] ) : Char = {
   if(areAllCharEquals(mapChar) == false) mapChar.keys.toList(1)
   else 0.toChar
 }

 /**Convert char to hexadecimal values as "0xHEXVALUE" */
 def charToHexString ( c : Char) : String = "0x" + c.toHexString

 /**Display results as asked in the ask*/
 def reportResults( s : String) : String = {
   val mapChar = countChar(s)
   if (areAllCharEquals(mapChar)) s + " -- length " + s.size + " -- contains all the same character."
   else {
     val diffChar = findFirstDifferentChar(mapChar)
     s + " -- length " + s.size + 
       " -- contains a different character at index " + 
       (s.indexOf(diffChar).toInt+1).toString + " : " + charToHexString(diffChar)
   }
 }

 def main(args: Array[String]): Unit = {
   println(reportResults(""))
   println(reportResults("   "))
   println(reportResults("2"))
   println(reportResults("333"))
   println(reportResults(".55"))
   println(reportResults("tttTTT"))
   println(reportResults("4444 444k"))
 }

}

</lang>

Output:

 -- length 0 -- contains all the same character.
    -- length 3 -- contains all the same character.
2 -- length 1 -- contains all the same character.
333 -- length 3 -- contains all the same character.
.55 -- length 3 -- contains a different character at index 2 : 0x35
tttTTT -- length 6 -- contains a different character at index 4 : 0x54
4444 444k -- length 9 -- contains a different character at index 5 : 0x20

Sidef

<lang ruby>func analyze_string(str) {

   var chars = str.chars
   chars.range.to_a.each_cons(2, {|a,b|
       chars[a] == chars[b] || return b
   })
   return str.len

}

var strings = ["", " ", "2", "333", ".55", "tttTTT", "4444 444k", "pépé", "🐶🐶🐺🐶", "🎄🎄🎄🎄"]

strings.each {|str|

   print "'#{str}' (size #{str.len}): "
   var idx = analyze_string(str)

   if (idx == str.len) {
       say "all the same."
   }
   else {
       say "first different char '#{str[idx]}' (#{'%#x' % str[idx].ord}) at position #{idx}."
   }

}</lang>

Output:

'' (size 0): all the same.
'   ' (size 3): all the same.
'2' (size 1): all the same.
'333' (size 3): all the same.
'.55' (size 3): first different char '5' (0x35) at position 1.
'tttTTT' (size 6): first different char 'T' (0x54) at position 3.
'4444   444k' (size 11): first different char ' ' (0x20) at position 4.
'pépé' (size 4): first different char 'é' (0xe9) at position 1.
'🐶🐶🐺🐶' (size 4): first different char '🐺' (0x1f43a) at position 2.
'🎄🎄🎄🎄' (size 4): all the same.

Standard ML

<lang Standard ML> datatype result=allSame | difference of string*char*int ; val chkstring = fn input => let val rec chk = fn ([],n) => allSame

              |  ([x],n)    => allSame

| (x::y::t,n)=> if x=y then chk (y::t,n+1) else difference (Int.fmt StringCvt.HEX(Char.ord(y)),y,n) in ( input, String.size input , chk ( String.explode input,2 ) ) end; </lang> result (string, string length, same or (hex,char,position)) <lang> - map chkstring [ ""," ","1","333",".55","tttTTT","4444 444k" ]; val it =

  [("", 0, allSame), ("   ", 3, allSame), ("1", 1, allSame),
   ("333", 3, allSame), (".55", 3, difference ("35", #"5", 2)),
   ("tttTTT", 6, difference ("54", #"T", 4)),
   ("4444 444k", 9, difference ("20", #" ", 5))]:

</lang>

Tcl

<lang tcl>package require Tcl 8.6 ; # For binary encode

array set yesno {1 Yes 0 No}

set test {

   {}
   {   }
   {2}
   {333}
   {.55}
   {tttTTT}
   {4444 444k}
   {jjjjjjj}

}

Loop through test strings

foreach str $test {

   set chars [dict create] ; # init dictionary
   set same 1
   set prev {}
   # Loop through characters in string
   for {set i 0} {$i < [string length $str]} {incr i} {
       set c [string index $str $i] ; # get char at index
       if {$prev == {}} {
           set prev $c ; # initialize prev if it doesn't exist
       }
       if {$c != $prev} {
           set same 0
           break ; # Found a different char, break out of the loop
       }
   }

   # Handle Output
   puts [format "Tested: %12s (len: %2d). All Same? %3s. " \
             "'$str'" [string length $str] $yesno($same)]
   if {! $same} {
       puts [format " --> Different character '%s' (hex: 0x%s) appears at index: %s." \
                 $c [binary encode hex $c] $i]
   }

}</lang>

Output:

Tested:           '' (len:  0). All Same? Yes.
Tested:        '   ' (len:  3). All Same? Yes.
Tested:          '2' (len:  1). All Same? Yes.
Tested:        '333' (len:  3). All Same? Yes.
Tested:        '.55' (len:  3). All Same?  No.
 --> Different character '5' (hex: 0x35) appears at index: 1.
Tested:     'tttTTT' (len:  6). All Same?  No.
 --> Different character 'T' (hex: 0x54) appears at index: 3.
Tested:  '4444 444k' (len:  9). All Same?  No.
 --> Different character ' ' (hex: 0x20) appears at index: 4.
Tested:    'jjjjjjj' (len:  7). All Same? Yes.

VBA

Instr is a VBA Function which process the strings from left─to─right.

The Optional argument LowerUpper As Boolean can display True for "tttTTT", if you want.

SameCharacters("tttTTT", respons, False) or SameCharacters("tttTTT", respons) return False

SameCharacters("tttTTT", respons, True) return True (All characters are the same)

<lang vb> Sub Main_SameCharacters() Dim arr, i As Integer, respons As Integer

   arr = Array("", "   ", "2", "333", ".55", "tttTTT", "4444 444k", "111111112", " 123")
   For i = LBound(arr) To UBound(arr)
       If SameCharacters(arr(i), respons) Then
           Debug.Print "Analyze : [" & arr(i) & "], lenght " & Len(arr(i)) & " : " & " All characters are the same."
       Else
           Debug.Print "Analyze : [" & arr(i) & "], lenght " & Len(arr(i)) & " : " & " is different at position " & respons & ", character = '" & Mid(arr(i), respons, 1) & "', hexa : (0x" & Hex(Asc(Mid(arr(i), respons, 1))) & ")"
       End If
   Next

End Sub Function SameCharacters(sTxt, resp As Integer, Optional LowerUpper As Boolean = False) As Boolean Dim A As String, B As String, i As Integer, temp As Integer

   If Len(sTxt) > 1 Then
       If LowerUpper Then
           SameCharacters = UCase(sTxt) = String$(Len(sTxt), UCase(Left$(sTxt, 1)))
       Else
           SameCharacters = sTxt = String$(Len(sTxt), Left$(sTxt, 1))
       End If
       If Not SameCharacters Then resp = InStr(sTxt, Left$(Replace(sTxt, Left$(sTxt, 1), vbNullString), 1))
   Else
       SameCharacters = True
   End If

End Function</lang>

Output:

Analyze : [], lenght 0 :  All characters are the same.
Analyze : [   ], lenght 3 :  All characters are the same.
Analyze : [2], lenght 1 :  All characters are the same.
Analyze : [333], lenght 3 :  All characters are the same.
Analyze : [.55], lenght 3 :  is different at position 2, character = '5', hexa : (0x35)
Analyze : [tttTTT], lenght 6 :  is different at position 4, character = 'T', hexa : (0x54)
Analyze : [4444 444k], lenght 9 :  is different at position 5, character = ' ', hexa : (0x20)
Analyze : [111111112], lenght 9 :  is different at position 9, character = '2', hexa : (0x32)
Analyze : [ 123], lenght 4 :  is different at position 2, character = '1', hexa : (0x31)

Visual Basic .NET

Translation of: C#

<lang vbnet>Module Module1

   Sub Analyze(s As String)
       Console.WriteLine("Examining [{0}] which has a length of {1}:", s, s.Length)
       If s.Length > 1 Then
           Dim b = s(0)
           For i = 1 To s.Length
               Dim c = s(i - 1)
               If c <> b Then
                   Console.WriteLine("    Not all characters in the string are the same.")
                   Console.WriteLine("    '{0}' (0x{1:X02}) is different at position {2}", c, AscW(c), i - 1)
                   Return
               End If
           Next
       End If
       Console.WriteLine("    All characters in the string are the same.")
   End Sub

   Sub Main()
       Dim strs() = {"", "   ", "2", "333", ".55", "tttTTT", "4444 444k"}
       For Each s In strs
           Analyze(s)
       Next
   End Sub

End Module</lang>

Output:

Examining [] which has a length of 0:
    All characters in the string are the same.
Examining [   ] which has a length of 3:
    All characters in the string are the same.
Examining [2] which has a length of 1:
    All characters in the string are the same.
Examining [333] which has a length of 3:
    All characters in the string are the same.
Examining [.55] which has a length of 3:
    Not all characters in the string are the same.
    '5' (0x35) is different at position 1
Examining [tttTTT] which has a length of 6:
    Not all characters in the string are the same.
    'T' (0x54) is different at position 3
Examining [4444 444k] which has a length of 9:
    Not all characters in the string are the same.
    ' ' (0x20) is different at position 4

Wren

Translation of: Go

Library: Wren-fmt

<lang ecmascript>import "/fmt" for Conv, Fmt

var analyze = Fn.new { |s|

   var chars = s.codePoints.toList
   var le = chars.count
   System.print("Analyzing %(Fmt.q(s)) which has a length of %(le):")
   if (le > 1) {
       for (i in 1...le) {
           if (chars[i] != chars[i-1]) {
               System.print("  Not all characters in the string are the same.")
               var c = String.fromCodePoint(chars[i])
               var hex = Conv.hex(chars[i])
               System.print("  '%(c)' (0x%(hex)) is different at position %(i+1).\n")
               return
           }
       }
   }
   System.print("  All characters in the string are the same.\n")

}

var strings = [

   "",
   "   ",
   "2",
   "333",
   ".55",
   "tttTTT",
   "4444 444k",
   "pépé",
   "🐶🐶🐺🐶",
   "🎄🎄🎄🎄"

] for (s in strings) analyze.call(s)</lang>

Output:

Analyzing "" which has a length of 0:
  All characters in the string are the same.

Analyzing "   " which has a length of 3:
  All characters in the string are the same.

Analyzing "2" which has a length of 1:
  All characters in the string are the same.

Analyzing "333" which has a length of 3:
  All characters in the string are the same.

Analyzing ".55" which has a length of 3:
  Not all characters in the string are the same.
  '5' (0x35) is different at position 2.

Analyzing "tttTTT" which has a length of 6:
  Not all characters in the string are the same.
  'T' (0x54) is different at position 4.

Analyzing "4444 444k" which has a length of 9:
  Not all characters in the string are the same.
  ' ' (0x20) is different at position 5.

Analyzing "pépé" which has a length of 4:
  Not all characters in the string are the same.
  'é' (0xe9) is different at position 2.

Analyzing "🐶🐶🐺🐶" which has a length of 4:
  Not all characters in the string are the same.
  '🐺' (0x1f43a) is different at position 3.

Analyzing "🎄🎄🎄🎄" which has a length of 4:
  All characters in the string are the same.

XPL0

<lang XPL0>include xpllib; \contains StrLen function

proc StrSame(S); \Show if string has same characters char S; int L, I, J, K; [L:= StrLen(S); IntOut(0, L); Text(0, ": ^""); Text(0, S); ChOut(0, ^"); CrLf(0); for I:= 0 to L-1 do

   for J:= I+1 to L-1 do
       [if S(I) # S(J) then
               [ChOut(0, \tab\ 9);
               for K:= 0 to J do ChOut(0, ^ );
               Text(0, "^^ Not same character: ");
               ChOut(0, S(J));
               Text(0, ", hex ");
               SetHexDigits(2);
               HexOut(0, S(J));
               CrLf(0);
               return;
               ];
       ];

Text(0, " All same character"); CrLf(0); ];

[Text(0, "Length"); CrLf(0); StrSame(""); StrSame(" "); StrSame("2"); StrSame("333"); StrSame(".55"); StrSame("tttTTT"); StrSame("4444 444k"); ]</lang>

Output:

Length
0:      ""
        All same character
3:      "   "
        All same character
1:      "2"
        All same character
3:      "333"
        All same character
3:      ".55"
          ^ Not same character: 5, hex 35
6:      "tttTTT"
            ^ Not same character: T, hex 54
9:      "4444 444k"
             ^ Not same character:  , hex 20

zkl

<lang zkl>fcn stringSameness(str){ // Does not handle Unicode

  sz,unique,uz := str.len(), str.unique(), unique.len();
  println("Length %d: \"%s\"".fmt(sz,str));
  if(sz==uz or uz==1) println("\tSame character in all positions");
  else
     println("\tDifferent: ",
       unique[1,*].pump(List,

'wrap(c){ "'%s' (0x%x)[%d]".fmt(c,c.toAsc(), str.find(c)+1) })

       .concat(", "));

}</lang> <lang zkl>testStrings:=T("", " ", "2", "333", ".55", "tttTTT", "4444 444k"); foreach s in (testStrings){ stringSameness(s) }</lang>

Output:

Length 0: ""
	Same character in all positions
Length 3: "   "
	Same character in all positions
Length 1: "2"
	Same character in all positions
Length 3: "333"
	Same character in all positions
Length 3: ".55"
	Different: '5' (0x35)[2]
Length 6: "tttTTT"
	Different: 'T' (0x54)[4]
Length 9: "4444 444k"
	Different: ' ' (0x20)[5], 'k' (0x6b)[9]