01  #include<stdio.h>
02  
03  int add(int,int); // fun_prototype
04  
05  int main()
06  {
07  int ans;
08  
09  int (*p)(int,int);
10  
11  /*
12  p is a pointer to a function,
13  which take 2 integers arguments
14  and return an integer.
15  */
16  
17  p=add;  // p now points to add function
18  
19  
20  ans=(*p)(10,20); // calling of add() funtion using function pointer
21  
22  
23  printf("answer is %d",ans);
24  
25  return 0;
26  }
27  
28  int add(int a,int b)
29  {
30  return (a+b);
31  }

 OUTPUT :
 
 answer is 30