myString.h

#pragma once
#include <iostream>
using namespace std;class myString
{
public:myString();myString(int len);myString(const myString& Str);myString(const char* str);~myString();//char& getString();//多余int getLen();myString& operator+(myString& str);myString& operator=(myString& str);char& operator[](int index);bool operator==(const myString& str)const;//const修饰this指针bool operator!=(const myString& str)const;bool operator>(const myString& str)const;bool operator<(const myString& str)const;private:char* m_p;int m_len;friend istream& operator>>(istream& in, myString& str);friend ostream& operator<<(ostream& out, myString& str);
};

myString.cpp

#define _CRT_SECURE_NO_WARNINGS
#include "myString.h"myString& myString::operator=(myString& str)
{if (this->m_p != NULL){delete[] m_p;m_p = NULL;m_len = 0;}this->m_len = str.m_len;m_p = new char[this->m_len + 1];for (int i = 0; i < m_len; i++){this->m_p[i] = str.m_p[i];}return *this;
}char& myString::operator[](int index)
{return m_p[index];
}bool myString::operator==(const myString& str) const
{if (this->m_len != str.m_len)return false;else{for (int i = 0; i < m_len; i++){if (this->m_p[i] != str.m_p[i])return false;}return true;}
}bool myString::operator!=(const myString& str) const
{return !(*this == str);
}bool myString::operator>(const myString& str) const
{if (strcmp(this->m_p, str.m_p) > 0)return true;else{return false;}
}bool myString::operator<(const myString& str) const
{if (strcmp(this->m_p, str.m_p) < 0)return true;else{return false;}
}istream& operator>>(istream& in, myString& str)
{char buf[1024] = { 0 };char* tmp = buf;cout << "请输入1个字符串:";in >> tmp;str.m_len = strlen(tmp);str.m_p = new char[str.m_len + 1];strcpy(str.m_p, buf);return in;
}ostream& operator<<(ostream& out, myString& str)
{for (int i = 0; i < str.m_len; i++){out << str.m_p[i];}out << endl;// TODO: 在此处插入 return 语句return out;
}myString::myString()
{this->m_len = 0;this->m_p = NULL;
}myString::myString(int len)
{this->m_len = len;m_p = new char[m_len + 1];
}myString::myString(const myString& Str)
{this->m_len = Str.m_len;m_p = new char[m_len + 1];strcpy(m_p, Str.m_p);
}myString::myString(const char* str)
{this->m_len = strlen(str);this->m_p = new char[this->m_len + 1];for (int i = 0; i < m_len; i++){this->m_p[i] = str[i];}
}myString::~myString()
{if (this->m_p != NULL){delete[] m_p;m_p = NULL;m_len = 0;}
}int myString::getLen()
{return this->m_len;
}myString& myString::operator+(myString& str)
{//int len = m_len + str.m_len;strcat(this->m_p, str.m_p);return *this;
}

myStringMain.cpp

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include "myString.h"
using namespace std;int main()
{myString s1(5), s2(5);cin >> s1;cout << s1 << endl;cin >> s2;cout << s2 << endl;myString s3(10);cout << s1[2] << endl;if (s1 == s2)cout << "===" << endl;if (s1 > s2)cout << "s1 > s2" << endl;if (s1 < s2)cout << "s1 < s2" << endl;return 0;
}