scanf_s with validation

validation.c

// this while loop is active as long as the user didn't input anything or
// their input is out of range
while (validation == 0) {
    validation = scanf_s("%d", &day);
    // this if is true when either the input is wrong (no number given)
    // or when the number is too low/high
    if (validation != 1 || day < 1 || day > 31) {
        // if validation is 0, the input buffer exists, so I DESTROY it
        while ((c = getchar()) != '\n' && c != EOF);
        printf("\nSorry, this was the wrong input. You need to give an \
integer between 1 and 31. Try again: ");
        // validation could be one, and then the while loop exists, so we
        // set it to 0. Happens when day is too high or low
        validation = 0;
    }
}

// reset validation so we can reuse the while loop
validation = 0;