//劍指offer面試題1：過載運算子函式
//題目：如下為型別CMyString的宣告，請為該型別新增多種運算子函式。
#include<iostream>
#include<cstring>
#include<cstdio>

using namespace std;

class CMyString
{
    friend ostream& operator<<(ostream &out, const CMyString &str);//輸出流過載函式
    friend istream& operator>>(istream &in, CMyString &str);//輸入流過載函式
 

public:
    CMyString(char* pData = nullptr);   //有參建構函式
    CMyString(const CMyString& str);    //拷貝建構函式
    ~CMyString(void);                   //解構函式

    CMyString& operator = (const CMyString &str);//過載賦值運算子函式
    CMyString& operator += (const CMyString &str);//過載+=運算子函式
    CMyString& operator
 
 + (const CMyString &str);//過載+運算子函式

    void show();
private:
    char* m_pData;
};

ostream &operator<<(ostream &out, const CMyString &str)
{
    out << str.m_pData << endl;
    return out;
}

istream &operator>>(istream &in, CMyString &str)
{
    in >> str.m_pData;
    return
 
 in;
}

CMyString::CMyString(char *pData)
{
    if (pData == nullptr)
    {
        m_pData = new char[1];
        m_pData[0] = '\0';      //'\0'表示空字元，作為字串結束符使用
    }
    else
    {
        m_pData = new char[strlen(pData) + 1];
        strcpy(m_pData, pData);
    }
}

CMyString::CMyString(const CMyString &str)
{
    m_pData = new char[strlen(str.m_pData) + 1];
    m_pData = str.m_pData;
}

CMyString::~CMyString()
{
    delete[] m_pData;
}

CMyString& CMyString::operator = (const CMyString &str)
{
    //判斷傳入的引數和當前的例項（*this）是不是同一個例項
    if (this == &str)
        return *this;

    //分配新記憶體之前釋放自身已有的記憶體，防止程式出現記憶體洩漏
    delete[]m_pData;
    m_pData = nullptr;

    m_pData = new char[strlen(str.m_pData) + 1];
    strcpy(m_pData, str.m_pData);

    return *this;
}

CMyString& CMyString::operator += (const CMyString &str)
{
    char *str1; //臨時的字串存放指標
    if (str.m_pData == nullptr)
        return *this;
    else
    {
        str1 = new char[strlen(m_pData) + strlen(str.m_pData) + 1];
        strcpy(str1, m_pData);
        strcat(str1, str.m_pData);
    }
    delete[]m_pData;
    m_pData = str1;
    return *this;

}
CMyString& CMyString::operator + (const CMyString &str)
{
    char *temp;//臨時的字串存放指標
    if (str.m_pData == nullptr)
        return *this;
    else
    {
        temp = new char[strlen(m_pData) + strlen(str.m_pData) + 1];
        strcpy(temp, m_pData);
        strcat(temp, str.m_pData);
    }
    delete[]m_pData;
    m_pData = temp;
    return *this;

}
//===============測試程式碼========================//
void CMyString::show()
{
    cout << m_pData << endl;
}


//賦值過載函式測試
void Test1()
{
    cout << "******************Test1(賦值)*****************" << endl;
    char *text = "Hello world";

    CMyString str1(text);
    CMyString str2;
    str2 = str1;
    cout << "The expected result is:" << text << endl;

    cout << "The actual result is:";
    str2.show();
    cout << endl;
}

//加法過載函式測試
void Test2()
{
    cout << "*********************Test2(加法)******************" << endl;
    char *text1 = "shuang";
    char *text2 = "is a beautiful girl!";

    CMyString str1(text1);
    CMyString str2(text2);
    CMyString str;
    cout << "The expected result is:" << text1 << " " << text2 << endl;
    str1 += str2;
    cout << "str1 += str2:";
    str1.show();

    CMyString str3 = "hai";
    CMyString str4 = "Merry";
    str = str3 + str4;
    cout << "str3 + str4:" << str << endl;
    //str3.show();

}

//輸入輸出流測試
void Test3()
{
    CMyString str1;
    CMyString str2;
    cin >> str1 >> str2;
    cout << "str1:" << str1 << endl;
    cout << "str2:" << str2 << endl;
}


int main(int argc, char *argv[])
{
    Test1();
    Test2();
    Test3();
    return 0;
}