WAP to copy string without changing source string

/*WAP to copy string without changing source string */

#include<stdio.h>
#include<conio.h>
main( )
{
 char  source[ ] = "codezworld" ;
 char  target[20] ;

 xstrcpy ( target, source ) ;
 printf ( "\nsource string = %s", source ) ;
 printf ( "\ntarget string = %s", target ) ;
}

void xstrcpy ( char *t, const char *s )
{
 while ( *s != '\0' )
 {
  *t = *s ;
  s++ ;
  t++ ;
 }
 *t = '\0' ;
}