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

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);
 }

2) Which of the following statements are correct about the program?

#include<stdio.h>
int main()
 {
     printf("%p\n", main());
     return 0;
 }

3) What will be the output of the program?

#include<stdio.h>
int reverse(int);
int main()
{
     int no=5;
     reverse(no);
     return 0;
 }
int reverse(int no)
 {
     if(no == 0)
         return 0;
     else
         printf("%d,", no);
     reverse (no--);
 }

4) What will be the output of the program?

#include<stdio.h>
int fun(int, int);
 typedef int (*pf) (int, int);
 int proc(pf, int, int);
int main()
 {
     printf("%d\n", proc(fun, 6, 6));
     return 0;
 }
 int fun(int a, int b)
 {
    return (a==b);
 }
int proc(pf p, int a, int b)
 {
    return ((*p)(a, b));
 }

5) What will be the output of the program?

#include<stdio.h>
void fun(int);
typedef int (*pf) (int, int);
int proc(pf, int, int);
int main()
 {
     int a=3;
     fun(a);
     return 0;
 }
void fun(int n)
 {
     if(n > 0)
     {
         fun(--n);
         printf("%d,", n);
         fun(--n);
     }
 }