C++ 类，运算符重载--->代码

最新推荐文章于 2024-11-08 14:09:27 发布

deepxl

最新推荐文章于 2024-11-08 14:09:27 发布

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分类专栏： linux C++ 学习文章标签： c++ delete 文档 null

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本文详细介绍了C++中自定义字符串类的实现方法，包括构造函数、复制构造函数、析构函数、赋值运算符、长度获取、空字符串判断、流插入运算符和字符串连接运算符的实现。并通过实例展示了如何使用该类进行字符串操作。

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/*mystring.h*/
#include <iostream>
using namespace std;

class MyString
{
friend ostream &operator<<(ostream &,const MyString &);
friend MyString operator+(const MyString&,const MyString &);

public:
	MyString(const char *);
	MyString(const MyString &);
	~MyString(void);
	MyString&operator=(const MyString &);
	int length(void)const;
	bool isEmpty(void)const;
private:
	char *data;
	int len;
};

/*mystring.cpp*/
#include <iostream>
#include "mystring.h"
#include <cstring>
using namespace std;

MyString::MyString(const char *str)
{
cout<<"ctor"<<endl;
if(str==NULL)
{
len=0;
data=new char[1];
*data='\0';
}else{
len=strlen(str);
data=new char[len+1];
strcpy(data,str);
}

}
MyString::MyString(const MyString &other)
{
cout<<"copy ctor"<<endl;

len=other.len;
data=new char [len+1];
strcpy(data,other.data);

}
MyString::~MyString(void)
{
cout<<"assignment"<<endl;
delete[]data;
}
MyString &MyString::operator=(const MyString &other)
{
cout<<"assignment"<<endl;
if(this==&other) //注意自己
return *this;
delete[]data;//注意以前的长度不狗

len=other.len;
data=new char[len+1];
strcpy(data,other.data);
return *this;
}
int MyString::length(void )const
{
return len;
}
bool MyString::isEmpty(void )const
{
return len==0;
}
ostream& operator<<(ostream &out,const MyString &str)
{
out<<str.data;
return out;
}
MyString operator+(const MyString &a,const MyString &b)
{
cout<<"concatenate"<<endl;
MyString temp("");

delete[]temp.data;
temp.len=a.len+b.len;
temp.data=new char[temp.len+1];
strcpy(temp.data,a.data);
strcat(temp.data,b.data);

return temp;
}

/*main.cpp*/
#include <iostream>
#include "mystring.h"

using namespace std;

int main()
{
	cout<<"----------NO.1--start----------"<<endl;
	MyString str("Hello");  //NO.1
	cout<<"----------NO.1--END----------"<<endl;

	cout<<"----------NO.2--start----------"<<endl;
	MyString str1=str;     //NO.2
	cout<<"----------NO.2--END----------"<<endl;
	cout<<"Length of str1:"<<str1.length()<<endl;
	cout<<"Value of str1:"<<str<<endl;

	cout<<"----------NO.3--start----------"<<endl;
	MyString str2="";//NO.3
	cout<<"----------NO.3--END----------"<<endl;
	cout<<"ls str2 empty()?"<<(str2.isEmpty()?"ture":"false")<<endl;
	
	cout<<"----------NO.4--start----------"<<endl;
	str2="world"; //NO.4
	cout<<"----------NO.4--END----------"<<endl;
	cout<<"Now value of str2"<<str2<<endl;

	cout<<"Now value of str:"<<str1+str2<<endl;
	cout<<"Value of another expression:"<<str1+"__world"<<endl;
	cout<<"Value of yet another expression:"<<"hello,"+str2<<endl;

	cout<<"----------NO.5--start----------"<<endl;
	MyString str3=str1+str2; //NO.5
	cout<<"----------NO.5--END----------"<<endl;

	cout<<"Value of str3:"<<str3<<endl;

	return 0;

}