C++编写字符串类CNString，该类有默认构造函数、类的拷贝函数、类的析构函数及运算符重载

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编码实现字符串类CNString，该类有默认构造函数、类的拷贝函数、类的析构函数及运算符重载，需实现以下“=”运算符、“+”运算、“[]”运算符、“<”运算符及“>”运算符及“==”运算符

以下为各个运算符的运算效果的详细说明：

a) 字符串“=”重载运算符

CNStringstr1("abc ");

CNString str2 = str1;

b) 字符串“+”运算

CNStringstr1("abc");

CNStringstr2("efg ");

str1 = str1 + str2;

c) 字符串“[]”运算

CNString nstring1("abc");

cout<< nstring1[0] ;// 则屏幕显示a

cout<< nstring1[2] ; // 则屏幕显示c

d) “<”运算符

CNStringstr1("abc");

CNStringstr2("efg");

if (str1 <str2 ){

cout<<“str1<str2”<<endl;

}

e) “>”运算符

CNStringstr1("abc");

CNStringstr2("efg");

if (str1 >str2 ){

cout<<“str1>str2”<<endl;

}

f) “==”运算符

CNStringstr1("abc");

CNStringstr2("efg");

if (str1 == str2){

cout<<“str1==str2”<<endl;

}

代码实现：

#include<iostream>
#include<string.h>
using namespace std;class CNString
{
private:
char *str_F;
public:
CNString(){str_F=NULL;};//默认构造函数
CNString(char *str);//有参构造函数
CNString(const CNString &other);//类的拷贝函数
~CNString();//类的析构函数
CNString &operator=(const CNString &obj);//"="号重载
CNString &operator+(const CNString &obj);//"+"号重载
char& operator[](int i);//"[]"号重载
bool operator<(const CNString &obj);//"<"号重载
bool operator>(const CNString &obj);//">"号重载
bool operator==(const CNString &obj);//"=="号重载
void print()//打印str_F的结果
{
cout<<str_F<<endl;
}
};
CNString::CNString(char *str)
{
str_F = new char(strlen(str)+);
if(str_F!=) strcpy(str_F,str);
}
CNString::CNString(const CNString &obj)
{
str_F = new char(strlen(obj.str_F)+);
if(str_F!=) strcpy(str_F,obj.str_F);
}
CNString::~CNString()
{
delete []str_F;
}
CNString & CNString::operator=(const CNString &obj)
{
char * tem=new char(strlen(obj.str_F)+);
strcpy(tem,obj.str_F);
str_F=tem;
delete[]tem;
return *this;
}
CNString & CNString::operator+(const CNString &obj)
{
strcat(str_F,obj.str_F);
return *this;
}
char &CNString::operator[](int i)
{
return str_F[i];
}
bool CNString::operator<(const CNString &obj)
{
int c = strcmp(str_F,obj.str_F);
if(c<) return true;
else return false;
}
bool CNString::operator>(const CNString &obj)
{
int c = strcmp(str_F,obj.str_F);
if(c>) return true;
else return false;
}
bool CNString::operator==(const CNString &obj)
{
int c = strcmp(str_F,obj.str_F);
if(c==) return true;
else return false;
}
int main()
{
CNString str1("abc ");
CNString str2("edf");
CNString str3;
cout<<"实现运算符+和=重载后："<<endl;
str3 = str1 + str2;
str3.print();
cout<<"实现运算符[]重载后："<<endl;
CNString nstring1("abc");
cout<<nstring1[]<<endl;
cout<<"实现运算符'<' '>' '=='重载后："<<endl;
if (str1 <str2 )
{
cout<<"str1<str2"<<endl;
}
if (str1 >str2 )
{
cout<<"str1>str2"<<endl;
}
if(str1==str2)
{
cout<<"str1==str2"<<endl;
}
return ;
}