Input / Output - General Questions

What does scanf return at end of input?

What will be the output of the program?

#include <stdio.h>

int main(void) {
    printf("%d%%\n", 50);
    return 0;
}

What does scanf("%d", &n) return when it successfully reads one integer?

What will be the output of the program?

#include <stdio.h>

int main(void) {
    putchar('Y');
    putchar('e');
    putchar('s');
    putchar('\n');
    return 0;
}

What will be the output of the program?

#include <stdio.h>

int main(void) {
    printf("%c%c\n", 72, 'i');
    return 0;
}