MyString类

MyString.h

#ifndef MYSTRING_H
#define MYSTRING_H#include <iostream>
using namespace std;class MyString
{private:char*  str = nullptr;unsigned int MaxSize = 0;public:MyString();                /*默认构造函数*/MyString(unsigned int n);  /*有参构造函数*/MyString(const char* S);   /*有参构造函数*/MyString(const MyString& S);                  /*拷贝构造函数*/MyString& operator= (const MyString& S);      /*拷贝赋值运算符重载*/~MyString();  /*析构函数*/MyString( MyString && S) noexcept;            /*移动构造函数*/MyString& operator= (MyString&& S) noexcept;  /*移动赋值运算符重载*/friend ostream& operator<< (ostream& Output, MyString& S);friend istream& operator>> (istream& Input, MyString& S);char& operator[] (unsigned int i);//   const char& operrator[] (unsigned int i)  const ;
};
#endif

MyString.c

#include "MyString.h"/*获取字符串长度*/
unsigned int Length(const char* S)
{const char* p = S;unsigned int L = 0;while (*p != '\0'){p++;L++;}return L;
}
/*默认构造函数*/
MyString::MyString()
{cout << "无参构造函数：";
}
/*创建可包含n个字符的空字符串*/
MyString::MyString(unsigned int n)
{MaxSize = n + 1;str = new char[MaxSize] {};
}
/*构造函数，写入字符串*/
MyString::MyString(const char* S)
{MaxSize = Length(S) + 1;str = new char[MaxSize] {};for (unsigned int i = 0; i < (MaxSize - 1); i++){str[i] = S[i];}str[MaxSize - 1] = '\0';cout << "有参构造函数：" ;
}
/*拷贝构造函数*/
MyString::MyString(const MyString& S)
{MaxSize = S.MaxSize;str = new char[MaxSize] {};for (unsigned int i = 0; i < MaxSize; i++){str[i] = S.str[i];}cout << "拷贝构造函数：";
}
/*拷贝赋值运算符重载*/
MyString& MyString::operator= (const MyString& S)
{delete[] str;MaxSize = S.MaxSize;str = new char[MaxSize] {};for (unsigned int i = 0; i < MaxSize; i++){str[i] = S.str[i];}cout << "拷贝赋值运算符重载：";return *this;
}
/*析构函数*/
MyString::~MyString()
{if (str != nullptr)delete[] str;cout << "析构函数" << endl;
}
/*移动构造函数*/
MyString::MyString(MyString&& S) noexcept
{delete[] str;MaxSize = S.MaxSize;str =S.str;S.str = nullptr;cout << "移动构造函数：";
}
/*移动赋值运算符重载*/
MyString& MyString::operator= (MyString&& S) noexcept
{delete[] str;MaxSize = S.MaxSize;str = S.str;S.str = nullptr;cout << "移动赋值运算符重载：";return *this;
}ostream& operator<< (ostream& Output, MyString& S)
{Output << S.str;return Output;
}
istream& operator>> (istream& Input, MyString& S)
{Input >> S.str;return Input;
}char& MyString::operator [] (unsigned int i) 
{return str[i];
}

main.c

#include <iostream>
using namespace std;#include "MyString.h"MyString GetMyString(void)
{MyString temp = "C++";return temp;
}void MyString_Test(void)
{MyString S1;         //无参构造函数cout << "S1 " << endl;char str[] = { "Hello World!" };MyString S2{ str };   //有参构造函数cout << "S2 " << S2 << endl;MyString S3{ S2 };    //拷贝构造函数cout << "S3 " << S3 << endl;S1 = S3;             //拷贝赋值运算符重载cout << "S1 " << S1 << endl;MyString S4{ move(S1) };  //移动构造函数// MyString S4{ GetMyString() };    cout << "S4 " << S4 << endl;S4 = GetMyString();  //移动赋值运算符重载cout << "S4 " << S4 << endl;MyString S5{ 3 };S5[0] = 'A';S5[1] = 'B';S5[2] = 'C';cout << S5 << endl;
}int main()
{MyString_Test();
}

结果：