string参考

#include <iostream>
#include <string.h>
class string
{
private:
    char *data;
public:
    string(const char *data = NULL);
    string(const string& str);
    ~string();
    void print();
    int size();
    int SetValue();

};

string::string(const char *data )
{
    if(data == NULL)
    {
        this->data = new char[];
        //this->data = '\0';
        strcpy(this->data,"");
    }
    else
    {
        this->data = new char[strlen(data)+];
        strcpy(this->data,data);
    }
}
string::string(const string& str)
{
//    std::cout << "拷贝构造函数" << endl;
    this->data = new char[strlen(str.data)+];
    strcpy(this->data,str.data);
}
string::~string()
{
    delete []data;
}
void string::print()
{
    std::cout << data << std::endl;
}

int string::size()
{
    return strlen(data);
}

int string::SetValue()
{
    data[] = 'H';
}
int main()
{
    string str;
    string str1 = str;
    str1.SetValue();
    str1.print();
    str.print();
}