手撕代码，实现String类的构造函数、拷贝构造函数、赋值构造函数以及析构函数

#include <bits/stdc++.h>
using namespace std;

class String {
public:
    String(const char* str = NULL){// 普通构造函数
        cout << "普通构造函数被调用" << endl;
        if (str == NULL) {
            data = new char[1];
            *data = '\0';
        }
        else {
            int len = strlen(str);
            data = new char[len + 1];
            for (int i = 0;i < len;i++)
                data[i] = str[i];
            data[len] = '\0';
        }
    }

    String(const String &other) {// 拷贝构造函数
        cout << "拷贝构造函数被调用" << endl;
        int len = strlen(other.data);
        data = new char[len + 1];
        for (int i = 0;i < len;i++)
            data[i] = other.data[i];
        data[len] = '\0';
    }

    ~String() { //析构函数
        cout << "析构函数被调用" << endl;
        delete[]data; // 释放内存
        data = NULL;   // 置空指针
    }
    String& operator = (const String &other) { //赋值构造函数
        cout << "赋值运算符构造函数被调用" << endl;int len = strlen(other.data);
        data = new char[len + 1];
        for (int i = 0;i < len;i++)
            data[i] = other.data[i];
        data[len] = '\0';
        return *this;
    }
    void show() {
        cout << data << endl;
    }
private:
    char* data;
};

int main()
{
    {
        String s("hello");
        s.show();
        String ss = String(s); //拷贝构造函数调用
        ss.show();
        String sss = s; //赋值
        sss.show();
    }
    system("pause");
    

    return 0;
}