class String

{
public:
String(const char *str = NULL);//普通構造函數
String(const String &other);//拷貝構造函數
~String(void);//普通析構函數
String &operator = (const String &other);//賦值函數
protected:
private:
char *m_data;
};
String::~String(void)

{
delete []m_data;
}
String::String(const char *str /**//* = NULL */)

{
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(const String &other)

{
int length = strlen(other.m_data);
m_data = new char[length+1];
strcpy(m_data,other.m_data);
}
String &String::operator=(const String &other)

{
if(this == &other)
{
return *this;
}
delete []m_data;
int length = strlen(other.m_data);
m_data = new char[length+1];
strcpy(m_data,other.m_data);
return *this;
}
int main(int argc, char* argv[])

{
String str("Hello");
String str1 = str;
String str2;
str2 = str;
return 0;
} 

