Case-sensitivity of identifiers

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Revision as of 05:50, 28 May 2013 by rosettacode>Bengt (Added Erlang)
Task
Case-sensitivity of identifiers
You are encouraged to solve this task according to the task description, using any language you may know.

Three dogs (Are there three dogs or one dog?) is a code snippet used to illustrate the lettercase sensitivity of the programming language. For a case-sensitive language, the identifiers dog, Dog and DOG are all different and we should get the output:

The three dogs are named Benjamin, Samba and Bernie.

For a language that is lettercase insensitive, we get the following output:

There is just one dog named Bernie.

Cf.

Ada

case insensitive <lang Ada>with Ada.Text_IO; procedure Dogs is

  Dog : String := "Bernie";

begin

  Ada.Text_IO.Put_Line ("There is just one dog named " & DOG);

end Dogs;</lang>

Output:

There is just one dog named Bernie

AutoHotkey

<lang AutoHotkey>dog := "Benjamin" Dog := "Samba" DOG := "Bernie" MsgBox There is just one dog named %dOG%</lang>

AWK

<lang awk>BEGIN { dog = "Benjamin" Dog = "Samba" DOG = "Bernie" printf "The three dogs are named %s, %s and %s.\n", dog, Dog, DOG }</lang>

The three dogs are named Benjamin, Samba and Bernie.

BBC BASIC

<lang bbcbasic> dog$ = "Benjamin"

     Dog$ = "Samba"
     DOG$ = "Bernie"
     PRINT "The three dogs are " dog$ ", " Dog$ " and " DOG$ "."</lang>

Output:

The three dogs are Benjamin, Samba and Bernie.

bc

The only variables are 'a' through 'z'. They can only hold numbers, not strings. Some implementations allow longer names like 'dog', but only with lowercase letters. A name like 'Dog' or 'DOG' is a syntax error.

<lang bc>obase = 16 ibase = 16

/*

* Store the hexadecimal number 'BE27A312'
* in the variable 'd'.
*/

d = BE27A312 "There is just one dog named "; d quit</lang>

There is just one dog named BE27A312

Brlcad

The three dogs are drawn as spheres in this simple example:

<lang mged> opendb dogs.g y # Create a database to hold our dogs units ft # The dogs are measured in feet in dog.s sph 0 0 0 1 # Benjie is a little Scottie dog in Dog.s sph 4 0 0 3 # Samba is a Labrador in DOG.s sph 13 0 0 5 # Bernie is massive. He is a New Foundland echo The three dogs are named Benjamin, Samba and Bernie</lang>

C

C is case sensitive; if it would be case insensitive, an error about redefinition of a variable would be raised.

<lang c>#include <stdio.h>

static const char *dog = "Benjamin"; static const char *Dog = "Samba"; static const char *DOG = "Bernie";

int main() {

   printf("The three dogs are named %s, %s and %s.\n", dog, Dog, DOG);
   return 0;

}</lang>

C#

C# is case sensitive <lang C sharp> using System;

class Program {

   static void Main(string[] args)
   {
       string dog = "Benjamin";
       string Dog = "Samba";
       string DOG = "Bernie";
       Console.WriteLine(string.Format("The three dogs are named {0}, {1}, and {2}.", dog, Dog, DOG));
   }

}</lang>

COBOL

<lang cobol *>* Case sensitivity of identifiers

      *>* Commented-out lines in the working storage
      *>* are considered as invalid redefinitions
      *>* of dog that can only be ambiguously
      *>* referenced in the procedure body.
      IDENTIFICATION DIVISION.
      PROGRAM-ID. case-sensitivity.
      DATA DIVISION.
      WORKING-STORAGE SECTION.
      *>* 01  dog PICTURE X(8) VALUE IS "Benjamin".
      *>* 01  Dog PICTURE X(5) VALUE IS "Samba".
      01  DOG PICTURE X(6) VALUE IS "Bernie".
      PROCEDURE DIVISION.
        DISPLAY
      *>*     "The three dogs are named "
      *>*     dog ", " Dog " and " DOG "."
          "There is just one dog named " DOG "."
        END-DISPLAY
        STOP RUN.
      END PROGRAM case-sensitivity.</lang>

CoffeeScript

<lang coffeescript> dog="Benjamin" Dog = "Samba" DOG = "Bernie" console.log "The three dogs are names #{dog}, #{Dog}, and #{DOG}." </lang>

output <lang> > coffee foo.coffee The three dogs are names Benjamin, Samba, and Bernie. </lang>

Common Lisp

<lang lisp>CL-USER> (let* ((dog "Benjamin") (Dog "Samba") (DOG "Bernie")) (format nil "There is just one dog named ~a." dog))

in
LAMBDA NIL
(LET* ((DOG "Benjamin") (DOG "Samba") (DOG "Bernie"))
(FORMAT NIL "There is just one dog named ~a." DOG))
caught STYLE-WARNING
The variable DOG is defined but never used.
caught STYLE-WARNING
The variable DOG is defined but never used.
compilation unit finished
caught 2 STYLE-WARNING conditions

"There is just one dog named Bernie."</lang>

These are the style warnings from SBCL. Other implementations of Common Lisp might give different warnings.

D

<lang d>import std.stdio;

void main() {

   string dog = "Benjamin";
   // identifiers that start with capital letters are type names
   string Dog = "Samba";
   string DOG = "Bernie";
   writefln("There are three dogs named ",
            dog, ", ", Dog, ", and ", DOG, "'");

}</lang> Output:

There are three dogs named Benjamin, Samba, and Bernie'

dc

A register name has only one character, so this example uses 'd' and 'D'.

<lang dc>[Benjamin]sd [Samba]sD [The two dogs are named ]P ldP [ and ]P lDP [. ]P</lang>

The two dogs are named Benjamin and Samba.

Delphi

<lang Delphi>program CaseSensitiveIdentifiers;

{$APPTYPE CONSOLE}

var

 dog: string;

begin

 dog := 'Benjamin';
 Dog := 'Samba';
 DOG := 'Bernie';
 Writeln('There is just one dog named ' + dog);

end.</lang>

Output:

There is just one dog named Bernie

DWScript

<lang Delphi> var dog : String;

dog := 'Benjamin'; Dog := 'Samba'; DOG := 'Bernie';

PrintLn('There is just one dog named ' + dog);</lang>

Output:

There is just one dog named Bernie

Erlang

Erlang variables are case sensitive but must start with an uppercase letter. <lang Erlang> -module( case_sensitivity_of_identifiers ).

-export( [task/0] ).

task() -> catch dog = "Benjamin", % Function will crash without catch Dog = "Samba", DOG = "Bernie", io:fwrite( "The three dogs are named ~s, ~s and ~s~n", [dog, Dog, DOG] ). </lang>

Output:
4> case_sensitivity_of_identifiers:task().
The three dogs are named dog, Samba and Bernie

Euphoria

Works with: Euphoria version 4.0.0

<lang Euphoria>-- These variables are all different sequence dog = "Benjamin" sequence Dog = "Samba" sequence DOG = "Bernie" printf( 1, "The three dogs are named %s, %s and %s\n", {dog, Dog, DOG} )</lang>

Fortran

Works with: Fortran version 90 and later

Fortran is case insensitive <lang fortran>program Example

 implicit none
 character(8) :: dog, Dog, DOG
 dog = "Benjamin"
 Dog = "Samba"
 DOG = "Bernie"
 if (dog == DOG) then
   write(*,*) "There is just one dog named ", dog
 else
   write(*,*) "The three dogs are named ", dog, Dog, " and ", DOG
 end if

end program Example</lang> Output:

 There is just one dog named Bernie

Frink

Frink is case-sensitive. <lang frink>dog = "Benjamin" Dog = "Samba" DOG = "Bernie" println["There are three dogs named $dog, $Dog and $DOG"]</lang>

F#

F# is case-sensitive. <lang fsharp>let dog = "Benjamin" let Dog = "Samba" let DOG = "Bernie" printfn "There are three dogs named %s, %s and %s" dog Dog DOG</lang>

GAP

<lang gap># GAP is case sensitive ThreeDogs := function() local dog, Dog, DOG; dog := "Benjamin"; Dog := "Samba"; DOG := "Bernie"; if dog = DOG then Print("There is just one dog named ", dog, "\n"); else Print("The three dogs are named ", dog, ", ", Dog, " and ", DOG, "\n"); fi; end;

ThreeDogs();

  1. The three dogs are named Benjamin, Samba and Bernie</lang>

Go

Go is case sensitive. Further, visibility depends on case. See the Go entry under the Scope modifiers task. <lang go>package dogs

import "fmt"

// Three variables, three different names. // (It wouldn't compile if the compiler saw the variable names as the same.) var dog = "Salt" var Dog = "Pepper" var DOG = "Mustard"

func PackageSees() map[*string]int {

   // Print dogs visible from here.
   fmt.Println("Package sees:", dog, Dog, DOG)
   // Return addresses of the variables visible from here.
   // The point of putting them in a map is that maps store only
   // unique keys, so it will end up with three items only if
   // the variables really represent different places in memory.
   return map[*string]int{&dog: 1, &Dog: 1, &DOG: 1}

}</lang> <lang go>package main

import (

   . "dogs"
   "fmt"

)

func main() {

   // with the dogs package imported, there are three dogs.
   d := PackageSees()
   fmt.Println("There are", len(d), "dogs.\n")
   // Declaration of new variable dog.  It lives in this package, main.
   dog := "Benjamin"
   d = PackageSees()
   fmt.Println("Main sees:   ", dog, Dog, DOG)
   // Four dogs now.  two of the three visible from here are the
   // the same as ones in the dogs package.
   d[&dog] = 1
   d[&Dog] = 1
   d[&DOG] = 1
   fmt.Println("There are", len(d), "dogs.\n")
   // Not a declaration, just an assigment.  This assigns a new value to
   // the variable Dog declared in the package.  Dog is visible because
   // it begins with an upper case letter.
   Dog = "Samba"
   // same four dogs, same three visible, one just has a new name.
   d = PackageSees()
   fmt.Println("Main sees:   ", dog, Dog, DOG)
   d[&dog] = 1
   d[&Dog] = 1
   d[&DOG] = 1
   fmt.Println("There are", len(d), "dogs.\n")
   // Of course you can still declare a variable if you want to.  This
   // declares a new variable, shadowing DOG in the package and rendering
   // it inaccessable even though it begins with an upper case letter.
   var DOG = "Bernie"
   // five dogs now.  three visible from here.
   d = PackageSees()
   fmt.Println("Main sees:   ", dog, Dog, DOG)
   d[&dog] = 1
   d[&Dog] = 1
   d[&DOG] = 1
   fmt.Println("There are", len(d), "dogs.")

}</lang>

Output:
Package sees: Salt Pepper Mustard
There are 3 dogs.

Package sees: Salt Pepper Mustard
Main sees:    Benjamin Pepper Mustard
There are 4 dogs.

Package sees: Salt Samba Mustard
Main sees:    Benjamin Samba Mustard
There are 4 dogs.

Package sees: Salt Samba Mustard
Main sees:    Benjamin Samba Bernie
There are 5 dogs.

Groovy

Solution: <lang groovy>def dog = "Benjamin", Dog = "Samba", DOG = "Bernie" println (dog == DOG ? "There is one dog named ${dog}" : "There are three dogs named ${dog}, ${Dog} and ${DOG}.")</lang>

Output:

There are three dogs named Benjamin, Samba and Bernie.

Haskell

Identifiers are case sensitive in Haskell, but must start with a lower case letter.

<lang Haskell>import Text.Printf

main = printf "The three dogs are named %s, %s and %s.\n" dog dOG dOg

   where dog = "Benjamin"
         dOG = "Samba"
         dOg = "Bernie"</lang>

Icon and Unicon

The program below demonstrates the three dog task. All variants of Icon/Unicon have case sensitive variable names. But if one wasn't this would find it. <lang Icon>procedure main()

  dog := "Benjamin"
  Dog := "Samba"
  DOG := "Bernie"
  if dog == DOG then 
     write("There is just one dog named ", dog,".") 
  else 
     write("The three dogs are named ", dog, ", ", Dog, " and ", DOG, ".")

end</lang>

J

<lang j> NB. These variables are all different

  dog=: 'Benjamin'
  Dog=: 'Samba'
  DOG=: 'Bernie'
  'The three dogs are named ',dog,', ',Dog,', and ',DOG

The three dogs are named Benjamin, Samba, and Bernie </lang>

Java

<lang java>String dog = "Benjamin"; String Dog = "Samba"; //in general, identifiers that start with capital letters are class names String DOG = "Bernie"; //in general, identifiers in all caps are constants //the conventions listed in comments here are not enforced by the language System.out.println("There are three dogs named " + dog + ", " + Dog + ", and " + DOG + "'");</lang>

JavaScript

Javascript is case sensitive. <lang javascript>var dog="Benjamin"; var Dog = "Samba"; var DOG = "Bernie"; document.write("The three dogs are named " + dog + ", " + Dog + ", and " + DOG + ".");</lang>

K

<lang k>

 dog: "Benjamin"
 Dog: "Samba"
 DOG: "Bernie"
 "There are three dogs named ",dog,", ",Dog," and ",DOG

"There are three dogs named Benjamin, Samba and Bernie" </lang>

Liberty BASIC

NB the IDE warns you that there are similar variables named dog$, Dog$ & DOG$ <lang lb> dog$ = "Benjamin" Dog$ = "Samba" DOG$ = "Bernie" print "The three dogs are "; dog$; ", "; Dog$; " and "; DOG$; "."

end </lang> The three dogs are Benjamin, Samba and Bernie.

Lua

<lang lua>dog = "Benjamin" Dog = "Samba" DOG = "Bernie"

print( "There are three dogs named "..dog..", "..Dog.." and "..DOG.."." )</lang>

There are three dogs named Benjamin, Samba and Bernie.

Maple

<lang>> dog, Dog, DOG := "Benjamin", "Samba", "Bernie": > if nops( { dog, Dog, DOG } ) = 3 then > printf( "There are three dogs named %s, %s and %s.\n", dog, Dog, DOG ) > elif nops( { dog, Dog, DOG } ) = 2 then > printf( "WTF? There are two dogs named %s and %s.\n", op( { dog, Dog, DOG } ) ) > else > printf( "There is one dog named %s.\n", dog ) > end if: There are three dogs named Benjamin, Samba and Bernie.</lang>

Mathematica

<lang Mathematica>dog = "Benjamin"; Dog = "Samba"; DOG = "Bernie"; "The three dogs are named "<> dog <>", "<> Dog <>" and "<> DOG

-> "The three dogs are named Benjamin, Samba and Bernie"</lang>

MATLAB / Octave

<lang Matlab> dog = 'Benjamin';

 Dog = 'Samba';
 DOG = 'Bernie';
 printf('There are three dogs %s, %s, %s.\n',dog, Dog, DOG); </lang>

Output

  There are three dogs Benjamin, Samba, Bernie.  

Maxima

<lang maxima>/* Maxima is case sensitive */ a: 1$ A: 2$

is(a = A); false</lang>

Modula-2

<lang modula2>MODULE dog;

IMPORT InOut;

TYPE String = ARRAY [0..31] OF CHAR;

VAR dog, Dog, DOG  : String;

(* No compiler error, so the rest is simple *)

BEGIN

 InOut.WriteString ("Three happy dogs.");
 InOut.WriteLn

END dog.</lang>

Nemerle

<lang Nemerle>def dog = "Benjamin"; def Dog = "Samba"; def DOG = "Bernie"; WriteLine($"The three dogs are named $dog, $Dog, and $DOG");</lang>

NetRexx

NetRexx is not case sensitive: <lang NetRexx>/* NetRexx */ options replace format comments java crossref symbols nobinary

dog = "Benjamin"; Dog = "Samba"; DOG = "Bernie";

if dog == Dog & Dog == DOG & dog == DOG then do

 say 'There is just one dog named' dog'.'
 end

else do

 say 'The three dogs are named' dog',' Dog 'and' DOG'.'
 end

return </lang> Output:

There is just one dog named Bernie.

Nimrod

<lang Nimrod>var dog = "Benjamin" Dog = "Samba" DOG = "Bernie" echo("There is just one dog named " & doG)</lang>

OCaml

Identifiers in OCaml are lettercase sensitive, but the first letter has to be lowercase.

<lang ocaml>let () =

 let dog = "Benjamin" in
 let dOG = "Samba" in
 let dOg = "Bernie" in
 Printf.printf "The three dogs are named %s, %s and %s.\n" dog dOG dOg</lang>

PARI/GP

<lang parigp>dog="Benjamin"; Dog="Samba"; DOG="Bernie"; printf("The three dogs are named %s, %s, and %s.", dog, Dog, DOG)</lang>

Pascal

See Delphi

Perl

<lang perl># These variables are all different $dog='Benjamin'; $Dog='Samba'; $DOG='Bernie'; print "The three dogs are named $dog, $Dog, and $DOG \n"</lang>

Perl 6

<lang perl6>my $dog = 'Benjamin'; my $Dog = 'Samba'; my $DOG = 'Bernie'; say "The three dogs are named $dog, $Dog, and $DOG."</lang> The only place that Perl�pays any attention to the case of identifiers is that, for certain error messages, it will guess that an identifier starting lowercase is probably a function name, while one starting uppercase is probably a type or constant name. But this case distinction is merely a convention in Perl, not mandatory: <lang perl6>constant dog = 'Benjamin'; sub Dog() { 'Samba' } my &DOG = { 'Bernie' } say "The three dogs are named {dog}, {Dog}, and {DOG}."</lang>

PicoLisp

<lang PicoLisp>(let (dog "Benjamin" Dog "Samba" DOG "Bernie")

  (prinl "The three dogs are named " dog ", " Dog " and " DOG) )</lang>

Output:

The three dogs are named Benjamin, Samba and Bernie

Prolog

In Prolog, the initial of a variable must be a uppercase letter. So the task can't be completed but we can write this code : <lang Prolog>three_dogs :- DoG = 'Benjamin', Dog = 'Samba', DOG = 'Bernie', format('The three dogs are named ~w, ~w and ~w.~n', [DoG, Dog, DOG]). </lang> The output is :

?- three_dogs.
The three dogs are named Benjamin, Samba and Bernie.
true.

PureBasic

<lang PureBasic>dog$="Benjamin" Dog$="Samba" DOG$="Bernie" Debug "There is just one dog named "+dog$</lang>

Python

Python names are case sensitive: <lang python>>>> dog = 'Benjamin'; Dog = 'Samba'; DOG = 'Bernie' >>> print ('The three dogs are named ',dog,', ',Dog,', and ',DOG) The three dogs are named Benjamin , Samba , and Bernie >>> </lang>

R

<lang R>dog <- 'Benjamin' Dog <- 'Samba' DOG <- 'Bernie'

  1. Having fun with cats and dogs

cat('The three dogs are named ') cat(dog) cat(', ') cat(Dog) cat(' and ') cat(DOG) cat('.\n')

  1. In one line it would be:
  2. cat('The three dogs are named ', dog, ', ', Dog, ' and ', DOG, '.\n', sep = )</lang>

Output:

The three dogs are named Benjamin, Samba and Bernie.

Racket

The default setting for the Racket reader is to be case sensitive: <lang Racket>

  1. lang racket

(define dog "Benjamin") (define Dog "Samba") (define DOG "Bernie")

(if (equal? dog DOG)

   (displayln (~a "There is one dog named " DOG "."))
   (displayln (~a "The three dogs are named " dog ", " Dog ", and, " DOG ".")))

</lang> Output:

The three dogs are named Benjamin, Samba, and, Bernie.

If you need case insensitive identifiers, then use #ci to turn on case insensitivity: <lang Racket>

  1. lang racket
  2. ci(module dogs racket
    (define dog "Benjamin")
    (set! Dog "Samba")
    (set! DOG "Bernie")     
    (if (equal? dog DOG)
        (displayln (~a "There is one dog named " DOG "."))
        (displayln (~a "The three dogs are named " dog ", " Dog ", and, " DOG "."))))

(require 'dogs) </lang> Output:

There is one dog named Bernie.

Retro

Retro is case sensitive.

<lang Retro>: dog ( -$ ) "Benjamin" ;

Dog ( -$ ) "Samba" ;
DOG ( -$ ) "Bernie" ;

DOG Dog dog "The three dogs are named %s, %s, and %s.\n" puts</lang>

REXX

Normally, the REXX language is case insensative (with respect to language and variables).
But lower/upper/mixed variables names can be handled if you wish. <lang rexx>/*demonstrate case insensative REXX variable names. (for the most part).*/ dog = 'Benjamin' Dog = 'Samba' DOG = 'Bernie'

say copies('-',20) /*show a sep for visual clarity. */ say 'dog=' dog say 'Dog=' Dog say 'DOG=' DOG say copies('-',20) /*show a sep for visual clarity. */ say

x='dog'; dogname.x='Benjamin' x='Dog'; dogname.x='Samba' x='DOG'; dogname.x='Bernie'

say copies('=',20) /*show a sep for visual clarity. */ _='dog'; say 'dog=' dogname._ _='Dog'; say 'Dog=' dogname._ _='DOG'; say 'DOG=' dogname._ say copies('=',20) /*show a sep for visual clarity. */

                                      /*stick a fork in it, we're done.*/</lang>

output

--------------------
dog= Bernie
Dog= Bernie
DOG= Bernie
--------------------

====================
dog= Benjamin
Dog= Samba
DOG= Bernie
====================

Ruby

Ruby gives a special meaning to the first letter of a name. A lowercase letter starts a local variable. An uppercase letter starts a constant. So dog is a local variable, but Dog and DOG are constants. To adapt this task to Ruby, I added dOg and doG so that I have more than one local variable.

<lang ruby>module FiveDogs

 dog = "Benjamin"
 dOg = "Dogley"
 doG = "Fido"
 Dog = "Samba"   # this constant is FiveDogs::Dog
 DOG = "Bernie"  # this constant is FiveDogs::DOG
 names = [dog, dOg, doG, Dog, DOG]
 names.uniq!
 puts "There are %d dogs named %s." % [names.length, names.join(", ")]
 puts
 puts "The local variables are %s." % local_variables.join(", ")
 puts "The constants are %s." % constants.join(", ")

end</lang>

Output:

There are 5 dogs named Benjamin, Dogley, Fido, Samba, Bernie.

The local variables are dog, dOg, doG, names.
The constants are Dog, DOG.

Run BASIC

<lang runbasic> dog$ = "Benjamin" doG$ = "Smokey" Dog$ = "Samba" DOG$ = "Bernie" print "The 4 dogs are "; dog$; ", "; doG$; ", "; Dog$; " and "; DOG$; "." </lang>

Sather

Though by convention Sather uses all uppercase letters for class names, a variable can be all uppercase.

<lang sather>class MAIN is

 main is
   dog ::= "Benjamin";
   Dog ::= "Samba";
   DOG ::= "Bernie";
   #OUT + #FMT("The three dogs are %s, %s and %s\n", 
                dog, Dog, DOG);
 end;

end;</lang>

Outputs:

The three dogs are Benjamin, Samba and Bernie

Scala

<lang scala>val dog = "Benjamin" val Dog = "Samba" val DOG = "Bernie" println("There are three dogs named " + dog + ", " + Dog + ", and " + DOG + ".")</lang> Output:

There are three dogs named Benjamin, Samba, and Bernie.

Scheme

Output may differ depending on implementation. <lang scheme>(define dog "Benjamin") (define Dog "Samba") (define DOG "Bernie")

(if (eq? dog DOG)

       (begin (display "There is one dog named ")
               (display DOG)
               (display ".")
               (newline))
       (begin (display "The three dogs are named ")
               (display dog) (display ", ")
               (display Dog) (display " and ")
               (display DOG)
               (display ".")
               (newline)))</lang>

Seed7

<lang seed7>$ include "seed7_05.s7i";

const string: dog is "Benjamin"; const string: Dog is "Samba"; const string: DOG is "Bernie";

const proc: main is func

 begin
   writeln("The three dogs are named " <& dog <& ", " <& Dog <& " and " <& DOG <& ".");
 end func;</lang>

Smalltalk

Works with: GNU Smalltalk

Smalltalk's symbols are case sensitive.

<lang smalltalk>|dog Dog DOG| dog := 'Benjamin'. Dog := 'Samba'. DOG := 'Bernie'. ( 'The three dogs are named %1, %2 and %3' %

 { dog . Dog . DOG } ) displayNl.</lang>

Outputs:

The three dogs are named Benjamin, Samba and Bernie

Tcl

Tcl variable names are case sensitive: <lang tcl>set dog "Benjamin" set Dog "Samba" set DOG "Bernie" puts "The three dogs are named $dog, $Dog and $DOG"</lang> Which prints...

The three dogs are named Benjamin, Samba and Bernie

UNIX Shell

<lang sh>dog="Benjamin" Dog="Samba" DOG="Bernie" echo "The three dogs are named $dog, $Dog and $DOG."</lang>

The three dogs are named Benjamin, Samba and Bernie.

XPL0

XPL0 is normally case-insensitive, so there is really just one dog named Bernie. However, it has a command-line switch (/c) that turns case sensitivity on. All names must start with a capital letter (or an underline, so they can't clash with command words such as 'for'). Thus "dog" cannot be used as a name, but Dog, DOG and DoG (and For) can. The intent of the command-line switch (/c) is to detect inconsistent capitalizing of names such as Ascii and ASCII or CpuReg and CPUReg.

ZX Spectrum Basic

<lang basic>10 LET D$="Benjamin" 20 PRINT "There is just one dog named ";d$</lang>