C++ 手写String类

Posted 2023-02-04 每天告诉自己要努力

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

class String 
public:
    String() 
        buf = new char[1];
        buf[0] = '\\0';
        len = 0;
    
    ~String() 
        if (buf != nullptr) 
            delete [] buf;
            buf = nullptr;
        
    
    //有参构造
    String(const char* src) 
        if (src == nullptr) 
            len = 0;
            buf = new char[1];
            buf[0] = '\\0';
            return;
        
        len = strlen(src);
        buf = new char[len + 1];
        strcpy(buf, src);
    
    //拷贝
    String(const String& s) 
        len = s.len;
        buf = new char[len + 1];
        strcpy(buf, s.buf);
    
    //移动
    String(String& s) 
        len = s.len;
        buf = s.buf;
        s.buf = nullptr;
        s.len = 0;
    
    //赋值
    String& operator=(const String& s) 
        if (this == &s) return *this;
        len = s.len;
        buf = new char[len + 1];
        strcpy(buf, s.buf);
        return  *this;
    
    //左移运算符重载
    friend ostream& operator<<(ostream& os, String& s) 
        os << s.buf;
        return os;
    
    //输出大小
    size_t size() 
        return len;
    
private:
    size_t len;
    char* buf;
;

int main() 
    String s1("hello world");
    cout << s1.size() << " " << s1 << endl;

    String s2 = s1;
    cout << s2.size() << " "<< s2 << endl;
    String s3;
    cout << s3.size() << " " << s3 << endl;
    return 0;