C Programming - Functions

Which of the following statements are correct about the program?

#include<stdio.h>

int main()
{
    printf("%p\n", main());
    return 0;
}

There is a error in the below program. Which statement will you add to remove it?

#include<stdio.h>

int main()
{
    int a;
    a = f(10, 3.14);
    printf("%d\n", a);
    return 0;
}
float f(int aa, float bb)
{
    return ((float)aa + bb);
}

Which of the following statements are correct about the function?

long fun(int num)
{
    int i;
    long f=1;
    for(i=1; i<=num; i++)
        f = f * i;
    return f;
}