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#include "stdio.h"

int add(int a, int b)
{
	return (a+b);
}

int sub(int a, int b)
{
	return (a-b);
}

int calcu(int a, int b, int (*f)(int , int))	
{
       int result;
       result=(*f)(a,b);
       return result;
	
}	


int main()
{
	int m,n;
	m=calcu(7,5,add);
	n=calcu(10,2,sub);

	int (*minus)(int,int)=sub;
	int p;
	p=calcu(20,6,minus);

	printf("m=%d\nn=%d\np=%d\n",m,n,p);

	return 0;

}

/**
OCS101:~/cpl # gcc pointerToFuntions.c 
OCS101:~/cpl # ./a.out 
m=12
n=8
p=14

*/


	

C++ allows operations with pointers to functions. The typical use of this is for passing a function as an argument to another function, since these cannot be passed dereferenced. In order to declare a pointer to a function we have to declare it like the prototype of the function except that the name of the function is enclosed between parentheses () and an asterisk (*) is inserted before the name:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

// pointer to functions #include <iostream> using namespace std; int addition (int a, int b) { return (a+b); } int subtraction (int a, int b) { return (a-b); } int operation (int x, int y, int (*functocall)(int,int)) { int g; g = (*functocall)(x,y); return (g); } int main () { int m,n; int (*minus)(int,int) = subtraction; m = operation (7, 5, addition); n = operation (20, m, minus); cout <<n; return 0; }

8

In the example, minus is a pointer to a function that has two parameters of type int. It is immediately assigned to point to the function subtraction, all in a single line:

int (* minus)(int,int) = subtraction;