While loop in C

Question

Could anyone please explain to me why my while loop won't end when i enter character 'Q'? It kept on looping even though i set my boolean value to false when the user enter 'Q', it supposed to end after that scanf for char input.

My code:

#include <stdio.h>
typedef int bool;
#define true 1
#define false 0

int main(void) {
    char input;
    char output;
    bool tf = true;

    printf("Welcome to the Coder!\n");

    while (tf) {
        printf("Choose Input (H,A,B,Q) : ");
        scanf_s(" %c\n", &input);

        if (input == 'Q') {
            tf = false;
        }
        else {
            printf("Choose Output (H,A,B) : ");
            scanf_s(" %c\n", &output);
        }
    }

    return 0;
}

Answer 1

You should add if

(input == 'Q' || input == 'q') 

Also why did you add typedef int bool;? This was unneeded.

I replace scanf_s to scanf because my compiler doesn't recognize it(accidentally solving problem.

because it is better. When I compile this there was no errors.

Compiled - > Compiled Code

Answer 2

The problem is the weird case of scanf_s. Accord to MSDN, you read single characters using this syntax:

scanf_s(" %c", &input, 1);

Remove the \n from scanf_s and add the 1 parameter so it knows to read only 1 character.

Answer 3

I am suspecting that you are entering small letter q on your console:

I would suggest you to change your code to:

if (input == 'Q' || input == 'q') {
    tf = false;
}