What is the use of member pointers in C++?

Member pointers are used in C++ to access and operate member variables or member functions of an object, even if the member is determined at runtime. They provide a flexible way to access members and support dynamic binding and generic programming.

The purpose of member pointers in C++

Member pointers are pointers to class member variables or member functions. They provide a flexible way to access and manipulate class members, even if the members are determined at runtime.

Grammar

The syntax of member pointer is:

type (Class::*memberName);

where:

• type Is the type of member variable or member function.
• Class is the class name.
• memberName is the member name.

Create member pointers

You can create member pointers to member variables and member functions:

// 指向成员变量
int (Class::*memberVariablePtr);

// 指向成员函数
void (Class::*memberFunctionPtr)(int);

Use member pointers

You can call member pointers by using the -> operator:

// 指向成员变量
int value = obj->*memberVariablePtr;

// 指向成员函数
obj->*memberFunctionPtr(10);

Practical case - comparison object

Consider a Person class with two member variables name and age:

class Person {
public:
    string name;
    int age;
};

Using member pointers, we can create comparisonsPerson Object methods:

bool comparePerson(const Person& p1, const Person& p2) {
    return p1.*age < p2.*age;
}

This function accesses the age member variable through the member pointer and uses it for comparison.

Advantages

Member pointers have the following advantages:

• Dynamic access to class members at runtime.
• Provides a concise way to encapsulate object access.
• Allows the use of generic programming paradigms.

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