自己实现C++对象的引用计数

最新推荐文章于 2025-10-31 16:26:59 发布

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本文介绍了一个使用C++实现的智能字符串类，该类通过引用计数管理内存，避免了不必要的复制，展示了如何在C++中高效地处理字符串。文章详细解释了构造函数、拷贝构造函数、赋值运算符和析构函数的实现，以及如何输出当前引用计数。

String.h

#include <iostream>
#include <string>

class String {
public:
    String()
        : m_sp(new std::string()), m_count(new int(0)) {
            *m_count = 1;
            output();
            std::cout << "Current function is " << __func__ << std::endl;
    }
    String(const std::string &s)
        : m_sp(new std::string(s)), m_count(new int(0)) {
            *m_count = 1;
            output();
            std::cout << "Current function is " << __func__ << std::endl;
    }
    
    String(const String& obj) {
        m_sp = obj.m_sp;
        m_count = obj.m_count;
        *m_count += 1;
        output();
        std::cout << "Current function is " << __func__ << std::endl;
    }

    String &operator=(const String& rhs) {
    	--*m_count;
        if (*m_count == 0) {
            delete m_sp;
            delete m_count;
        }
        m_sp = rhs.m_sp;
        m_count = rhs.m_count;
        *m_count += 1;
        
        output();
        std::cout << "Current function is " << __func__ << std::endl;
        return *this;
    }

    ~String() {
        if (*m_count == 1) {
            output();
            std::cout << "Current function is " << __func__ << std::endl;
            delete m_count;
            delete m_sp;
        } else {
            output();
            std::cout << "Current function is " << __func__ << std::endl;
            --*m_count;
        }
    }

private:
    std::string * m_sp;
    int * m_count;

public:
    void output() {
        std::cout << "===================================================================" << std::endl;
        std::cout << "The count is " << *m_count << std::endl;
    }
};

main.cpp

#include <iostream>
#include <memory>
#include "String.h"

int main() {
    String a("abc");
    String b(a);
    String c("Def");
    c = a;
    c.output();
    b.output();
    return 0;
}