MyString字符串类

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MyString字符串类

包括：有参构造、拷贝构造、移动构造、析构、拷贝赋值和移动赋值。

MyString.h文件

#ifndef MYSTRING_H
#define MYSTRING_H#include <iostream>
using namespace std;class MyString
{private:char* str;unsigned int MaxSize;unsigned int Length = 0;public:MyString() = default;              /*默认构造函数*/MyString(unsigned int m);          /*构造函数，空字符串*/MyString(const char* S);           /*构造函数，写入字符串*/MyString(const MyString& S);       /*拷贝构造函数*/MyString( MyString && S) noexcept; /*移动构造函数*/~MyString();                       /*析构函数*//*获取字符串长度*/unsigned int GetLength();/*字符串输出*/friend ostream& operator<< (ostream& Output, MyString& S);/*字符串输入*/friend  istream& operator>> (istream& Input, MyString& S);/*获取单个字符*/char & operator[] (unsigned int i);/*添加或修改单个字符*/void at(char ch);void at(unsigned int i, char ch);/*字符串比较*/bool operator== (MyString & S2);bool operator> (MyString & S2);bool operator< (MyString & S2);/*拷贝赋值运算符重载*/MyString& operator= (MyString& S);/*移动赋值运算符重载*/MyString& operator= (MyString&& S) noexcept;/*字符串链接函数*/MyString operator+ (MyString& S2);
};#endif

MyString.cpp文件

#include "MyString.h"/*构造函数，空字符串*/
MyString::MyString(unsigned int m) :MaxSize(m)
{MaxSize += 1;str = new char[MaxSize] {};str[MaxSize-1] = '\0';cout << "空构造函数：";
}
/*构造函数，写入字符串*/
MyString::MyString(const char* S)
{const char* p = S;while (*p != '\0'){p++;Length++;}MaxSize = Length + 1;str = new char[MaxSize] {};for (unsigned int i = 0; i < Length; i++){str[i] = S[i];}str[Length] = '\0';cout << "字符串构造函数：" ;
}
/*拷贝构造函数*/
MyString::MyString(const MyString& S)
{Length = S.Length;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：";
}
/*移动构造函数*/
MyString::MyString(MyString&& S) noexcept
{Length = S.Length;MaxSize = S.MaxSize;str =S.str;S.str = nullptr;cout << "移动构造函数：";
}
/*析构函数*/
MyString::~MyString()
{delete[] str;cout << "析构函数" << endl;
}
/*返回字符串长度*/
unsigned int MyString::GetLength()
{return Length;
}
/*字符串输入*/
ostream& operator<< (ostream& Output, MyString& S)
{Output << S.str;return Output;
}
/*字符串输出*/
istream& operator>> (istream& Input, MyString& S)
{Input >> S.str;return Input;
}
/*获取单个字符*/
char & MyString::operator[] (unsigned int i)
{return str[i];
}
/*添加或修改单个字符*/
void  MyString::at(char ch)
{if (Length < MaxSize - 1)str[Length] = ch;Length++;
}
void MyString::at(unsigned int i, char ch)
{if( i < Length)str[i] = ch;
}
/*字符串比较函数*/
bool MyString::operator== (MyString & S2)
{char* str1 = str;char* str2 = S2.str;while (*str1 != '\0' || *str2 != '\0'){if (*str1 > *str2)return false;if (*str1 < *str2)return false;str1++;str2++;}return true;
}
bool MyString::operator> (MyString & S2)
{char* str1 = str;char* str2 = S2.str;while (*str1 != '\0' || *str2 != '\0'){if (*str1 > *str2)return true;if (*str1 < *str2)return false;str1++;str2++;}return false;
}
bool MyString::operator< (MyString & S2)
{char* str1 = str;char* str2 = S2.str;while (*str != '\0' || *str2 != '\0'){if (*str1 > *str2)return false;if (*str1 < *str2)return true;str1++;str2++;}return false;
}
/*赋值运算符重载*/
MyString & MyString::operator= (MyString& S)
{delete[] str;Length = S.Length;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;
}
/*移动赋值运算符重载*/
MyString& MyString::operator= (MyString&& S) noexcept
{delete[] str;Length = S.Length;MaxSize = S.MaxSize;str = S.str;S.str = nullptr;cout << "移动赋值运算符重载：";return *this;
}
/*字符串链接函数*/
MyString MyString::operator+ (MyString& S2)
{MaxSize += S2.MaxSize;char* temp = new char[MaxSize] {};for (unsigned int i = 0; i < Length; i++){temp[i] = str[i];}temp[Length] = ' ';Length += 1;for (unsigned int i = Length; i < MaxSize; i++){temp[i] = S2.str[i - Length];}Length += S2.Length;delete[]str;str = temp;return *this;
}

main.cpp测试：

#include <iostream>
using namespace std;#include "MyString.h"
MyString  GetString()
{//   MyString n =  "1234";
//    MyString m(2);MyString temp = "C++";return temp;
}
int main()
{MyString S1{ "Hello World!" };  //构造函数，字符串初始化cout << S1 <<' '<< S1.GetLength() << endl;MyString S2{ S1 } ;  //拷贝构造函数cout << S2 <<' '<< S2.GetLength() << endl;MyString S3{ 3 };   //构造函数，空字符串S3.at('A');S3.at('B');S3.at('C');cout << S3 <<' '<< S3.GetLength() << endl;S3[2] = 'Z';cout << S3[2] << endl;S1 =  S3;               /拷贝赋值cout << S1 << ' ' << S1.GetLength() << endl;cout << (S1 < S2) << endl;cout << (S1 > S2) << endl;cout << (S1 == S2) << endl;MyString S4{ move(S1) }; //移动构造函数cout << S4 << ' ' << S4.GetLength() << endl;S4 = GetString();      //移动赋值cout << S4 << ' ' << S4.GetLength() << endl;S4 = S2 + S3;cout << S4 << ' ' << S4.GetLength() << endl;
}