Which is the constructor and destructor of C++

This article mainly explains "which is the constructor and destructor of C++". The content of the explanation in this article is simple and clear, and it is easy to learn and understand. Please follow the train of thought of the editor. Let's study and learn which one is the constructor and destructor of C++.

1. Constructor

First of all, because the class is only a template, we cannot initialize the member variables when defining the class, for example, the following code is wrong:

Class circle {public: int initializer = 20; / / Error: data member initializers are not allowed.

Therefore, initialization can only occur during the creation of an object by the class, but some member variables cannot be accessed outside the class due to access permissions, so the following approach is sometimes invalid:

Circle C1; / / instantiate an object C1C1.m_L = 20; / / initialize the corresponding variable through the created object, but invalidate if missul is private access

To solve this problem, programmers can apply objects as well as standard data types, providing a special member function within the class, the "constructor", which is specifically used to initialize class objects when they are created. It is special because C++ has automatically provided the name and usage syntax for the constructor, and the programmer only needs to provide the definition of the method, that is, the class name (formal parameter list). Specifically, the constructor is defined as follows:

Class circle {public: int masked LactPublic: / / member function (method) circle (const int a) / / assign member variables through constructor {masks L = a;}}; circle C1 (20); / / call format cout