Function Pointer to Member Function in C++

In C++, function pointers enable users to treat functions as objects. They provide a way to pass functions as arguments to other functions. A function pointer to a member function is a pointer that points to a non-static member function of a class. In this article, we will learn how to use a function pointer to a member function in C++.

Function Pointer to Member Function in C++

In C++, functions can be treated as objects with the help of function pointers. A function pointer to a member function is a pointer that can refer to a member function of a specific class. Member functions differ from regular functions because they are associated with an instance of a class, which means they have an implicit this pointer that points to the object invoking the object. Following is the syntax to declare a function pointer to a member function:

Syntax

return_type (ClassName::*pointer_name)(argument_types) = &ClassName::member_function;

where:

• return_type: is the return type of the member function of the class.
• ClassName: is the name of the class to which the member function belongs.
• *pointer_name: is the name of the function pointer variable.
• argument_types: are the types of the arguments accepted by the member function.
• &ClassName::member_function: is the address of the member function being assigned to the function pointer.

C++ Program to Declare a Function Pointer to Member Function

The below example demonstrates how we can declare a function pointer to a member function in C++:

Result from the member function: 50

Time Complexity: O(1)
Auxiliary Space: O(1)

Explanation

• In the above example, we have defined a class MyClass with a member function add that takes two integers and returns their sum.We have then declared function pointer ptrToMemberFunc that points to the member function add.

• To call the member function using the function pointer, we have used the syntax (obj.*ptrToMemberFunc)(20, 30) where obj is the instance of the class and *ptrToMemberFunc dereferences the function pointer to call the member function with the arguments 20 and 30 of type int.