Function as Arguments

FUNCTION AS ARGUMENTS:

A function pointer (or subroutine pointer or procedure pointer) is a type of pointer supported by third-generation programming languages Instead of referring to data values, a function pointer points to executable code within memory. When dereferenced, a function pointer can be used to invoke the function it points to and pass it arguments just like a normal function call. Such an invocation is also known as an "indirect" call, because the function is being invoked indirectly through a variable instead of directly through a fixed name or address. Function pointers can be used to simplify code by providing a simple way to select a function to execute based on run-time values.

#include <iostream.h>

int add(int first, int second)

{

return first + second;

}

int subtract(int first, int second)

{

return first - second;

}

int operation(int first, int second, int (*functocall)(int, int))

{

return (*functocall)(first, second);

}

void main()

{

int  a, b;

int  (*plus)(int, int) = add;

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

a = operation(7, 5, plus);

b = operation(20, a, minus);

cout << "a = " << a << " and b = " << b << endl;

}