Function Pointer in C

A function pointer in C is a pointer that points to a function instead of a variable. It can be used to call a function indirectly, which allows for more flexible and dynamic code, such as passing functions as arguments to other functions or implementing callback mechanisms.

Definition

A function pointer holds the memory address of a function, and can be used to call that function. Instead of calling a function by its name, you can use a function pointer to call it. This can be useful for callback functions, dynamic function calling, or implementing polymorphism in C.

The syntax for declaring a function pointer is:

Syntax:

                        
return_type (*pointer_name)(parameter_types);

Example: Function Pointer

This example demonstrates how to declare and use a function pointer to call a function.

Example Code:

                        
#include <stdio.h>
        
// Function declaration
int add(int a, int b) {
   return a + b;
}
        
int subtract(int a, int b) {
    return a - b;
}
        
int main()
{
    // Declare a function pointer
    int (*func_ptr)(int, int);
        
    // Assign the function pointer to the add function
    func_ptr = add;
    printf("Addition: %d\n", func_ptr(5, 3));
        
    // Assign the function pointer to the subtract function
    func_ptr = subtract;
    printf("Subtraction: %d\n", func_ptr(5, 3));
        
    return 0;
}

Output

Addition: 8
Subtraction: 2

Key Points