2017년 5월 23일 화요일

[C++] MyString Copy Assignment (May 23)

#include <iostream>
#include <string>
#include <cstring>

using namespace std;

class MyString {

public:
    char* Buffer;
    //string Buffer;

public:
    /*
    // constructor
    MyString(string mystring) {
        cout << "Constructor: creating new MyString" << endl;
        Buffer = mystring;
        cout << "Buffer points to: 0x" << (void *)&Buffer[0] << endl;
    }
    */

    MyString(const char* mystring) {
        if (mystring != NULL) {
            Buffer = new char [strlen(mystring) + 1];
            strcpy(Buffer, mystring);

            // Display memory address pointed by local buffer
            cout << "Buffer points to: 0x" << hex;
            cout << (unsigned int*)Buffer << endl;
        }
        else
            Buffer = NULL;
    }

    // Copy Constructor
    MyString(const MyString& CopySource) {
        cout << "Copy Constructor" << endl;
        if (CopySource.Buffer != NULL) {
            Buffer = new char[strlen(CopySource.Buffer) + 1];
            strcpy(Buffer, CopySource.Buffer);

            cout << "CopySource Buffer points to: 0x" << hex;
            cout << (unsigned int*)CopySource.Buffer << endl;

            cout << "Buffer points to: 0x" << hex;
            cout << (unsigned int*)Buffer << endl;
        }
    }

    // Copy assignment operator
    MyString& operator= (const MyString& CopySource) {
        if ((this != &CopySource) && (CopySource.Buffer != NULL))
        {
            if (Buffer != NULL)
                delete[] Buffer;
            Buffer = new char [strlen(CopySource.Buffer) + 1];
            strcpy(Buffer, CopySource.Buffer);
        }
        return *this;
    }

    ~MyString() {

        cout << "Invoking destructor" << endl;

        if (Buffer != NULL)
            delete [] Buffer;
    }

    const char* GetString() {
        return Buffer;
    }

    int GetLength() {
        return strlen(Buffer);
    }

    operator const char*() {
        return Buffer;
    }
};

/*
void UseMyString(MyString Input)
{
    cout << "UseMyString Buffer points to : 0x" << (void *)&Input.Buffer[0] << endl;
    cout << "length: " << Input.Buffer.length();
    cout << "Buffer contains: " << Input.Buffer.c_str() << endl;

    return;
}
*/
int main()
{

    MyString SayHello("SayHello from the class");
    MyString String1("Hello");
    MyString String2("World");

    cout << String1 << String2 << endl;

    // UseMyString(SayHello);

    // cout << SayHello.GetString() << endl;

    return 0;
}