字符串类封装

MyString.h

#define _CRT_SECURE_NO_WARNINGS
#pragma once
#include <iostream>
using namespace std;
class MyString
{friend ostream& operator<< (ostream & out, MyString& str);friend istream& operator>>(istream& in, MyString& str);
public:MyString(const char *);MyString(const MyString&);~MyString();char& operator[](int index); //[]重载//=号重载MyString& operator=(const char * str);MyString& operator=(const MyString& str); //字符串拼接 重载+号MyString operator+(const char * str );MyString operator+(const MyString& str);//字符串比较bool operator== (const char * str);bool operator== (const MyString& str);
private:char * pString; //指向堆区空间int m_Size; //字符串长度 不算'\0'
};

MyString.cpp

#include "MyString.h"
//左移运算符
ostream& operator<< (ostream & out, MyString& str)
{out << str.pString;return out;
}
//右移运算符
istream& operator>>(istream& in, MyString& str)
{//先将原有的数据释放if (str.pString != NULL){delete[] str.pString;str.pString = NULL;}char buf[1024]; //开辟临时的字符数组，保存用户输入内容in >> buf;str.pString = new char[strlen(buf) + 1];strcpy(str.pString, buf);str.m_Size = strlen(buf);return in;
}
//构造函数
MyString::MyString(const char * str)
{this->pString = new char[strlen(str) + 1];strcpy(this->pString, str);this->m_Size = strlen(str);
}
//拷贝构造
MyString::MyString(const MyString& str)
{this->pString = new char[strlen(str.pString) + 1];strcpy(this->pString, str.pString);this->m_Size = str.m_Size;
}
//析构函数
MyString::~MyString()
{if (this->pString!=NULL){delete[]this->pString;this->pString = NULL;}
}
char& MyString::operator[](int index)
{return this->pString[index];
}
MyString& MyString::operator=(const char * str)
{if (this->pString != NULL){delete[] this->pString;this->pString = NULL;}this->pString = new char[strlen(str) + 1];strcpy(this->pString, str);this->m_Size = strlen(str);return *this;
}
MyString& MyString::operator=(const MyString& str)
{if (this->pString != NULL){delete[] this->pString;this->pString = NULL;}this->pString = new char[strlen(str.pString) + 1];strcpy(this->pString, str.pString);this->m_Size = str.m_Size;return *this;
}
MyString MyString::operator+(const char * str)
{int newsize = this->m_Size + strlen(str) + 1;char *temp = new char[newsize];memset(temp, 0, newsize);strcat(temp, this->pString);strcat(temp, str);MyString newstring(temp);delete[] temp;return newstring;
}
MyString MyString::operator+(const MyString& str)
{int newsize = this->m_Size + str.m_Size + 1;char *temp = new char[newsize];memset(temp, 0, newsize);strcat(temp, this->pString);strcat(temp, str.pString);MyString newstring(temp);delete[] temp;return newstring;
}
bool MyString::operator==(const char * str)
{if (strcmp(this->pString, str) == 0 && strlen(str) == this->m_Size){return true;}return false;
}
bool MyString::operator==(const MyString& str)
{if (strcmp(this->pString, str.pString) == 0 && str.m_Size == this->m_Size){return true;}return false;
}

TestMyString.cpp

void test01()
{MyString str("hello World");cout << str << endl;//cout << "请输入 MyString 类型字符串：" << endl;//cin >> str;//cout << "字符串为： " << str << endl;//测试[]cout << "MyString 的第一个字符为：" << str[0] << endl;//测试 =MyString str2 = "^_^";MyString str3 = "";str3 = "aaaa";str3 = str2;cout << "str2 = " << str2 << endl;cout << "str3 = " << str3 << endl;//测试 +MyString str4 = "我爱";MyString str5 = "北京";MyString str6 = str4 + str5;MyString str7 = str6 + "天安门";cout << str7 << endl;//测试 == if (str6 == str7){cout << "s6 与 s7 相等" << endl;}else{cout << "s6 与 s7 不相等" << endl;}
}