# include <stdio.h>
# include <stdlib.h>
//
//  We will need the IRAN function to set the secret number:
//
int iran ( int a, int b, int *seed );


int main ( )
{
  int guess;
  int seed;
  int secret;
  int turns;
//
//  Scramble the random number generator.
//
  seed = time ( 0 );
//
//  SEED is just a number, and you can print it out if you like.
//
  printf ( "SEED = %i\n", seed );
//
//  Get a secret value between 0 and 100.
//
  secret = iran ( 0, 100, &seed );
//
//  Torture the user.
//
  turns = 0;
  printf ( "Guess my number, or -1 to quit!\n" );

  while ( 1 )
  {
    scanf ( "%i", &guess );

    if ( guess == -1 ) 
    {
      printf ( "Sorry you got tired!  The secret number was %d\n", secret );
      break;
    }

    turns = turns + 1;

    if ( guess == secret )
    {
      printf ( "You got it!  My secret number was %d!\n", secret );
      break;
    }
    else if ( guess < secret )
    {
      printf ( "Higher!\n" );
    }
    else if ( secret < guess )
    {
      printf ( "Lower!\n" );
    }
  }

  printf ( "\n" );
  printf ( "You played for %i turns.\n", turns );

  return 0;
}

int iran ( int a, int b, int *seed )
//
//  IRAN returns a random integer between A and B.
{
  int i4_huge = 2147483647;
  int k;
  float value;
//
//  Check SEED.
//
  if ( *seed == 0 )
  {
    printf ( "\n" );
    printf ( "IRAN - Fatal error!\n" );
    printf ( "  Input value of SEED = 0.\n" );
    exit ( 1 );
  }
//
//  Update SEED.
//
  k = *seed / 127773;

  *seed = 16807 * ( *seed - k * 127773 ) - k * 2836;

  if ( *seed < 0 )
  {
    *seed = *seed + i4_huge;
  }
//
//  Use the MOD function.
//
  if ( b < a )
  {
    value = b + ( *seed % ( a - b ) );
  }
  else if ( b == a )
  {
    value = a;
  }
  else
  {
    value = a + ( *seed % ( b - a ) );
  }

  return value;
}