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) What will be the output of the program?

#include<stdio.h>
void fun(int*, int*);
int main()
 {
     int i=5, j=2;
     fun(&i, &j);
     printf("%d, %d", i, j);
     return 0;
 }
 void fun(int *i, int *j)
 {
     *i = *i**i;
     *j = *j**j;
 }

3) 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);
     }
 }

4) What will be the output of the program?

#include<stdio.h>
int main()
 {
     void fun(char*);
     char a[100];
     a[0] = 'A';
 a[1] = 'B';
     a[2] = 'C';
 a[3] = 'D';
     fun(&a[0]);
     return 0;
 }
 void fun(char *a)
 {
     a++;
     printf("%c", *a);
     a++;
     printf("%c", *a);
 }

5) 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;
 }