The code for my program works once and doesn't loop- gets an error on codeblocks and crashes

Question

The code is as follows: guessing game , 10 guesses max, prompts user for replay. It crashes after one run. It works fine without the replay() module but then I can't incorporate the replay option. I have tried several different things to no avail. Please kindly help me resolve this in a timely manner. Help is appreciated in advance. thanks

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void guessGame ();
int replay();
int main()
{

    int selection;


    printf("Welcome to the Number Guess Game! I choose a number between 1 and 100 and you\nhave only 10 chances to guess it!");

    do
    {

        printf("\n\nok, I made my mind!");
        guessGame();
        replay();
    }
    while (replay() != 0);

    printf("Thank you! have a nice day.\n");





    return 0;

}
void guessGame()
{
    int attempt,guess;
    srand(time(NULL));
    int r = rand () % 100 + 1;


    for (guess = 1; (guess < 11 && attempt != r); guess = guess + 1)
    {
        printf("\nWhat is your guess> ");
        scanf("%d",&attempt);
        if (attempt < 1 || attempt > 100)
        {
            printf("Invalid guess!\n");
            guess = guess - 1;
        }
        else
        {
            if (attempt > r && guess < 10)
                printf("My number is smaller than %d\n",attempt);
            else if (attempt < r && guess < 10)
                printf("My number is larger than %d\n",attempt);
        }

        if ((guess < 9) && (attempt >= 1 && attempt <= 100))
            printf("%d guesses left.\n",(10 - guess));
        if ((guess == 9) &&(attempt >= 1 && attempt <= 100))
            printf("%d guess left.\n",(10 - guess));
    }
    if (attempt == r)
    {
        printf("You did it! My number is %d.\nYou did it in %d guesses.\n",r,guess);
    }
    if (guess >= 10 && attempt != r)
    {
        printf("SORRY! you couldn't guess it with 10 guesses.\nMy number was %d. Maybe next time!\n",r);
    }



}

int replay()
{
    char selection;

    printf("\nDo you want to play again");
    scanf("%c",selection);
    if (selection == 'N')
        return 0;
    else
        return 1;
}

Answer 1

You're calling scanf() incorrectly. You need to give the address of the variables to store into:

scanf("%c", &selection);