string class

String.cpp

#include "String.h"

#include <string.h>

String::~String(void)
{
    delete[] _data;
    _data = NULL;
}

String::String(const char* data /*= NULL*/)
{
    if (NULL != data)
    {
        int size = strlen(data);
        _data = new char[size+1];
        strcpy(_data, data);
    }
    else
    {
        _data = NULL;
    }
}

String::String(const String& other)
{
    if (this != &other && NULL != other._data)
    {
        int size = strlen(other._data);
        _data = new char[size+1];
        strcpy(_data, other._data);
    }
}

String& String::operator+=(const String& other)
{
    if (NULL != other._data)
    {
        int otherSize = strlen(other._data);
        int selfSize = 0;
        if (NULL != _data)
        {
            selfSize = strlen(_data);
        }
        
        char* _newData = new char[otherSize+selfSize+1];

        if (NULL != _data)
        {
            strcpy(_newData, _data);
            delete[] _data;
            _data = NULL;
        }
        
        strcat(_newData, other._data);
        _data = _newData;
    }

    return *this;
}

String& String::operator=(const String& rhs)
{
    if (this != &rhs && NULL != rhs._data)
    {
        delete[] _data;

        int size = strlen(rhs._data);
        _data = new char[size+1];
        strcpy(_data, rhs._data);
    }

    return *this;
}

std::ostream& operator<<(std::ostream& os, String& str)
{
    os << str._data;
    return os;
}

String.h

#ifndef STRING_H
#define STRING_H

#include <iostream>

class String
{
    friend std::ostream& operator<< (std::ostream&, String&);
public:
    String(const char* data = NULL);
    String(const String& other);
    ~String(void);

    String& operator+=(const String& other);
    String& operator=(const String& rhs);

private:
    char* _data;
};



#endif // STRING_H