# include <stdio.h>

int main ( )
{
  char c;
  int diff;
  char lowa = 'a';
  char capa = 'A';
//
//  Remember that characters are "really" integers.
//
  printf ( "\n" );
  printf ( "  lowa, printed as a characters, is '%c'\n", lowa );
  printf ( "  lowa, printed as an integer, is %i\n", lowa );
  printf ( "\n" );
  printf ( "  capa, printed as a characters, is '%c'\n", capa );
  printf ( "  capa, printed as an integer, is %i\n", capa );
  printf ( "\n" );
  diff = lowa - capa;
  printf ( "  The difference lowa - capa = %i\n", diff );
  printf ( "  This difference can be used to capitalize a lowercase letter,\n" );
  printf ( "  or lowercase a capital letter.\n" );
  printf ( "\n" );

  for ( c = 'a'; c <= 'z'; c++ )
  {
    printf ( "  c = '%c' = %i, c - %i = '%c' = %i\n", c, c, diff, c - diff, c - diff );
  }

  printf ( "\n" );
  printf ( "  Now ADD the difference to uppercase letters:\n" );
  printf ( "\n" );

  for ( c = 'A'; c <= 'Z'; c++ )
  {
    printf ( "  c = '%c' = %i, c + %i = '%c' = %i\n", c, c, diff, c + diff, c + diff );
  }
  return 0;
}