Home > Backend Development > C++ > body text

When is User-Defined Copy Constructor Necessary in C ?

Susan Sarandon
Release: 2024-10-24 04:39:02
Original
264 people have browsed it

When is User-Defined Copy Constructor Necessary in C  ?

User-Defined Copy Constructor in C

In C , the compiler typically generates a default copy constructor for classes, which performs member-wise copying. However, in certain scenarios, a user-defined copy constructor is necessary.

When is a user-defined copy constructor needed?

A user-defined copy constructor is required when the default copy constructor's member-wise copying behavior is insufficient. Consider the following example:

<code class="cpp">class Class {
public:
    Class(const char* str);
    ~Class();
private:
    char* stored;
};

Class::Class(const char* str) {
    stored = new char[srtlen(str) + 1];
    strcpy(stored, str);
}

Class::~Class() {
    delete[] stored;
}</code>
Copy after login

In this example, the default copy constructor would simply copy the pointer to the stored member, rather than duplicating the underlying buffer. This can lead to undefined behavior if one copy is destroyed before the other.

User-Defined Copy Constructor

To address this, you can define a user-defined copy constructor that performs deep copying:

<code class="cpp">Class::Class(const Class& another) {
    stored = new char[strlen(another.stored) + 1];
    strcpy(stored, another.stored);
}</code>
Copy after login

This copy constructor allocates new memory and copies the contents of the stored member, ensuring that both copies have their own independent buffers.

The above is the detailed content of When is User-Defined Copy Constructor Necessary in C ?. For more information, please follow other related articles on the PHP Chinese website!

source:php
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template