Simple guessing game in c

Question

Hello I'm trying to write a simple number guessing game in c. If the player guesses the number correctly, the program will give a message and aks if the player want to play again.

When i compile the code, it generate the random number, let the player guess the number and check whether the number is right or not. But when it aks if the player want to play again, it does not let the player answer and instead just exit. I don not know why it happens. Can you please help me?

int main()
{ 

int number, guess_value,number_of_guesses;
char answer;

srand((unsigned)time(NULL));
number=rand() %100+1;

A:number_of_guesses=0;
while (guess_value != number){
    printf("\nEnter a number between 0 and 100\n");
    scanf("%d", &guess_value);      
    number_of_guesses++;
    if (guess_value == number){
        printf("Right !!! You win\n");
    }
    else if (guess_value > number){
        printf("\nYour guess is too high. Guess again");
    }
    else {printf("\nYour guess is too low. Guess again");
    }
}

printf("You guessed %d times !", number_of_guesses);

printf("Do you want to play again? y? n?");
scanf("%c", &answer);
if (answer == 'y'){ 
    goto A; /*return to to beginging*/
}
return 0;   
}

Answer 1

I think the problem is that you compare guess_value before initialization.

Answer 2

Corrected code is:

int main()
{
    int number, guess_value,number_of_guesses;
    char answer;

    srand((unsigned)time(NULL));

    do
    {
        number=rand() %100+1;
        number_of_guesses=0;
        do
        {
            printf("\nEnter a number between 0 and 100\n");
            scanf("%d", &guess_value);
            number_of_guesses++;
            if (guess_value == number)
            {
                printf("Right !!! You win\n");
            }
            else if (guess_value > number)
            {
                printf("\nYour guess is too high. Guess again");
            }
            else
            {
                printf("\nYour guess is too low. Guess again");
            }
        }
        while (guess_value != number);

        printf("You guessed %d times !\n", number_of_guesses);

        printf("Do you want to play again? y? n?");

        scanf(" %c", &answer);
    }
    while (answer == 'y');

    return 0;
}

Many thing are wrong in your code:

1. As already well explained by other users do not use goto statement
2. you must reset guess_value before entering the game while loop, or change the loop to a do{}while(guess_value != number)
3. You have to add a whitespace before the %c format specifier to consume "garbage" that belongs to the input buffer after the scanf("%d", &guess_value);
4. number variable must be init each while (answer == 'y'); loop. Otherwise it always use the same number to be guessed.

To be more specific about point 3 you must understand that the first scanf does not consume the '\n' (carriage return, enter keyboard key) char of user input. This char still in the input buffer until the second scanf is executed when '\n' is returned into answer variable. Finally when you check if (answer == 'y') the condition is always false.

Answer 3

avoid using goto statements. use do-while instead

do {
number=rand() %100+1;

number_of_guesses=0;
do {
    printf("\nEnter a number between 0 and 100\n");
    scanf("%d", &guess_value);      
    number_of_guesses++;
    if (guess_value == number){
        printf("Right !!! You win\n");
    }
    else if (guess_value > number){
        printf("\nYour guess is too high. Guess again");
    }
    else {printf("\nYour guess is too low. Guess again");
    }
} while (guess_value != number);

printf("You guessed %d times !", number_of_guesses);

printf("Do you want to play again? y? n?");
scanf("%c", &answer);
} while (answer == 'y');

This should fix your problem, it loops in the code until anything besides 'y' appears.

Answer 4

Your problem is that you should reset guess_value, otherwhise while will not be executed

Answer 5

#include<stdio.h>                           
#include<stdlib.h>                        //for rand & srand function
#include<time.h>                          //for time obviously. 
 int main()
{ 
int number, guess_value,number_of_guesses;
char answer;

A:                                       //put label here, Generate rand val every time. 
srand((unsigned)time(NULL));
number=rand() %100+1;

guess_value=0;                           //reset the guess value.
number_of_guesses=0;

while (guess_value != number){
  printf("\nEnter a number between 0 and 100\n");
  scanf("%d", &guess_value);      
  number_of_guesses++;
  if (guess_value == number){
    printf("Right !!! You win\n");
  }
  else if (guess_value > number){
    printf("\nYour guess is too high. Guess again");
  }
  else {printf("\nYour guess is too low. Guess again");
  }
}

printf("You guessed %d times !", number_of_guesses);
printf("Do you want to play again? y? n?");

getchar();                               //use this to remove the \n.
scanf("%c", &answer);
if (answer == 'y'){
goto A; /*return to to beginging*/
}

return 0;   
}

scanf gets the input from the input buffer, Every time a user hits the enter, \n gets to the buffer. After this scanf function, take the \n.

Answer 6

This works:

#include <stdio.h> // Include

int main() { 
    int number, guess_value, number_of_guesses;
    char answer;

    A:  
    srand(time(NULL)); // Fix
    number = rand() %100+1;
    number_of_guesses = 0;
    while(guess_value != number) {
        puts("\nEnter a number between 0 and 100\n");
        scanf("%d", &guess_value);      
        number_of_guesses++;
        if (guess_value == number) {
            printf("Right !!! You win\n");
        }
        else if (guess_value > number) {
            printf("\nYour guess is too high. Guess again");
        }
        else {
            printf("\nYour guess is too low. Guess again");
        }
    }

    printf("You guessed %d times !\n", number_of_guesses);
    puts("Do you want to play again? y? n?");
    scanf("%s", &answer); // Fix
    if (answer == 'y'){ 
         goto A;
    }
    return 0;   
}