/*  GuessAWord.c  (c) Kari Laitinen

    http://www.naturalprogramming.com/

    2013-11-22 File created.
    2013-11-22 Last modification.

    This program is a simple computer game in which the player has to
    guess the characters of a word, or the player may also try to guess
    the whole word.

    This program demonstrates, among other things, various string
    operations.
*/

#include  <stdio.h>
#include  <string.h>
#include  <stdbool.h> /* Definitions for bool, true, and false */

int main()
{
   printf( "\n This is a GUESS-A-WORD game.  \n" ) ;

   char word_to_be_guessed[] = "VIENNA" ;

   char guessed_characters[] = "________________________________________" ;

   guessed_characters[ strlen( word_to_be_guessed ) ] = 0 ;

   // Now guessed_characters refers to a string that has as many
   // underscore characters as the word to be guessed.

   bool game_is_over = false ;

   while ( game_is_over == false )
   {
      printf( " %s  Give a character or word: ", guessed_characters ) ;

      char player_input[ 30 ] ;

      gets( player_input ) ;

      // The following loop uses to bit operator & to convert the
      // player input to uppercase letters. (Note that this program may
      // not work with non-English letters.)

      int character_index ;

      for ( character_index = 0 ;
            character_index < strlen( player_input ) ;
            character_index ++ )
      {
         player_input[ character_index ] =
                             player_input[ character_index ] & 0xDF ;
      }

      if ( strlen( player_input ) == 1 )
      {
         // The player gave a single character

         for ( character_index = 0 ;
               character_index < strlen( word_to_be_guessed ) ;
               character_index ++ )
         {
            if ( word_to_be_guessed[ character_index ] == player_input[ 0 ] )
            {
               guessed_characters[ character_index ] = player_input[ 0 ] ;
            }
         }

         if ( strstr( guessed_characters, "_" ) == 0 )
         {
            // "_" is not a substring in guessed characters.
            // This means that all characters have been guessed.

            game_is_over = true ;

            printf( " %s  Congratulations! \n\n", guessed_characters ) ;
         }

      }
      else if ( strlen( player_input ) > 1 )
      {
         // The player tried to guess the whole word.

         if ( strcmp( player_input, word_to_be_guessed ) == 0 )
         {
            // The player made a correct guess.

            game_is_over = true ;

            printf( "\n Congratulations! \n\n" ) ;
         }
      }
      else
      {
         game_is_over = true ;

         printf( " \n Game over. \n\n" ) ;
      }
   } 
}