Stringクラスの練習

#include <iostream>

#include <cstring>

using namespace std;



class String

{

public:

    String(const char* str = NULL)

    {

        m_data = strcpy(new char[strlen(str?str:"")+1],str?str:"");

    }

    ~String()

    {

        if(m_data)

            delete[] m_data;

    }

    String(const String& that)

    {

        m_data=strcpy(new char[strlen(that.m_data)+1],that.m_data);

    }



    String& operator=(const String& that)

    {

        if(&that != this)

        {

            // 

            //delete[] m_data;

            //m_data = strcpy(new char[strlen(that.m_data)+1],that.m_data);



            // 

            //char* temp = new char[strlen(that.m_data)+1]);// ， ， 

            //delete[] m_data;

            //m_data = strcpy(temp,that.m_data);



            // 

            String str(that);

            swap(m_data,str.m_data); // 

        }

        return *this;

    }



    char* c_str() const

    {

        return m_data;

    }

private:

    char* m_data;

};



int main()

{

    String s1("Hello Word");

    cout << s1.c_str() << endl;

    String s2(s1);

    cout << s2.c_str() << endl;

    return 0;



}