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 %+d\n", 5, -5);
    return 0;
}

Which function writes a string followed by a newline to stdout?

What will be the output of the program?

#include <stdio.h>

int main(void) {
    printf("[%6.2f]\n", 3.14159);
    return 0;
}

What will be the output of the program?

#include <stdio.h>

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