String类的实现

#include<iostream>

using namespace std;

class String

{

public:

String(const char *str = NULL);

String(const String &other);

~String(void);

String & operator=(const String &other);

bool operator==(const String &str);

friend ostream & operator<<(ostream& o,const String &str);

private:

char *m_data;

};

/*

构造、析构、拷贝构造、赋值运、流输出运算

*/

String::String(const char *str)

{

if (str == NULL){

m_data = new char[1];

*m_data='\0';

}else{

int len=strlen(str);

m_data = new char[len+1];

strcpy(m_data,str);

}

}

String::~String(void)

{

delete [] m_data;

}

String::String(const String &other)

{

int len = strlen(other.m_data);

m_data = new char[len+1];

strcpy(m_data,other.m_data);

}

String & String::operator=(const String &other)

{

if (this == &other)

return *this;

delete []m_data;

int len = strlen(other.m_data);

m_data = new char[len+1];

strcpy(m_data,other.m_data);

return *this;

}

bool String::operator==(const String &str)

{

return strcmp(m_data,str.m_data) == 0;

}

ostream & operator<<(ostream &o,const String &str)

{

o<<str.m_data;

return o;

int main()

{

String s = "hello";

String s2 = s;

String ss = "hello";

cout<<"s = "<<s<<endl;

cout<<"s2 = "<<s2<<endl;

cout<<boolalpha<<(ss == s)<<endl;

}