# include <stdio.h>

char capital ( char c );

int main ( )
//
//  This program reads characters from the text file "input.txt",
//  and writes them, capitalized, to another file, "output.txt".
//
{
  char c;
  int check;
  FILE *input;
  FILE *output;

  input = fopen ( "input.txt", "rt" );
  output = fopen ( "output.txt", "wt" );

  while ( 1 )
  {
//
//  FGETC actually returns an INT, not a CHAR.
//  This is only so that it can return the special value EOF
//  when necessary.
//
//  The safest thing to do is store the result of GETCHAR in
//  an INT, and if the value is not EOF, copy the value into 
//  a character.
//
    check = fgetc ( input );
    if ( check == EOF )
    {
      break;
    }
    c = check;

    c = capital ( c );
    fputc ( c, output );
  }

  fclose ( input );
  fclose ( output );

  return 0;
}

char capital ( char c )
{
  if ( 'a' <= c && c <= 'z' )
  {
    c = c - 32;
  }
  return c;
}