int main(int argc, char* argv[])
{
    if(argc == 3)
    {
        (unsigned long)argv[1] ^= (unsigned long)argv[2] ^= (unsigned long)argv[1] ^= (unsigned long)argv[2];
        cout << argv[1] << "\n";
        cout << argv[2] << "\n";
 
    }
 
}

int main( int argc, char *argv[] ) {
  char *s1, *s2;
  int len, len2;
 
  if (argc < 3) {
    printf( "fooey!\n" );
    return 1;
    }
 
  /* len <-- size of the longest string */
  len  = strlen( argv[ 1 ] );
  len2 = strlen( argv[ 2 ] );
  len  = (len < len2) ? len2 : len;
 
  /* get the strings */
  s1 = (char *)malloc( len );
  s2 = (char *)malloc( len );
 
  strcpy( s1, argv[ 1 ] );
  strcpy( s2, argv[ 2 ] );
 
  printf( "Given the strings:\n" );
  printf( "1. %s\n", s1 );
  printf( "2. %s\n", s2 );
 
  /* (do your swap here) */
 
  printf( "Now the strings are:\n" );
  printf( "1. %s\n", s1 );
  printf( "2. %s\n", s2 );
 
  free( s2 );
  free( s1 );
  return 0;
  }

char a = '1', b = '2';
printf( "%c%c\n", a, b );
a ^= b, b ^= a, a ^= b;
printf( "%c%c\n", a, b );

#include <stdio.h>
 
int main ( int argc, char *argv[] )
{
  if ( argc > 2 ) {
    int i = 0;
 
    printf ( "Before: '%s' '%s'\n", argv[1], argv[2] );
 
    while ( argv[1][i] != '\0' ) {
      char save = argv[1][i];
      argv[1][i] = argv[2][i];
      argv[2][i++] = save;
    }
 
    printf ( "After:  '%s' '%s'\n", argv[1], argv[2] );
  }
 
  return 0;
}