面试题1：赋值运算符函数

 

/*******************************************************************
Copyright(c) 2017, htfeng
All rights reserved.
*******************************************************************/

//==================================================================
// 《剑指Offer——名企面试官精讲典型编程题》代码
//  作者：何海涛
//  C++
//==================================================================

// 面试题1：赋值运算符函数
// 题目：如下为类型CMyString的声明，请为该类型添加赋值运算符函数。

#include<iostream>
#include<string>

using namespace std;


// ===================创建类=====================
template<class T>
class CMyString {
public:
    CMyString(T* pData = nullptr);
    CMyString(const CMyString<T>& str);
    ~CMyString(void);

    CMyString<T>& operator = (const CMyString<T>& str);
    void print();

private:
    T* m_pData;
};

template<class T>
CMyString<T>::CMyString(T* pData) {
    if (pData == nullptr) {
        m_pData = new T[1];
        m_pData[0] = '\0';
    }
    else {
        int length = strlen(pData);
        m_pData = new T[length + 1];
        strcpy_s(m_pData, length + 1, pData);
    }
}

template<class T>
CMyString<T>::CMyString(const CMyString<T>& str) {
    int length = strlen(str.m_pData);
    m_pData = new T[length + 1];
    strcpy_s(m_pData, length+1, str.m_pData);
}

template<class T>
CMyString<T>::~CMyString() {
    delete[] m_pData;
}

template<class T>
CMyString<T>& CMyString<T>::operator=(const CMyString<T>& str) {
    if (this == &str)
        return *this;

    delete[] m_pData;
    m_pData = nullptr;

    int length = strlen(str.m_pData);
    m_pData = new T[length + 1];
    strcpy_s(m_pData, length + 1, str.m_pData);

    return *this;
}

//==================测试代码===================
template<class T>
void CMyString<T>::print() {
    cout << m_pData << endl;
}

// 把一个CMyString的实例赋值给另一个实例
void test1() {
    cout << "把一个CMyString的实例赋值给另一个实例:" << endl;

    char text[] = "hello test1";
    char *astr = text;
    CMyString<char> str1(astr);
    CMyString<char> str2;
    str2 = str1;

    cout << "The expected result is: " << text << endl;

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


//把一个CMyString的实例赋值给自己
void test2() {
    cout << "把一个CMyString的实例赋值给自己:" << endl;

    char text[] = "hello test2";
    char *astr = text;

    CMyString<char> str1(astr);
    str1 = str1;

    cout << "The expected result is: " << text << endl;

    cout << "The actual result is:";
    str1.print();
    cout << endl;
}

// 连续赋值
void test3() {
    cout << "连续赋值:" << endl;

    char text[] = "hello world!";
    char *astr = text;

    CMyString<char> str1(astr);
    CMyString<char> str2, str3;
    str3 = str2 = str1;

    cout << "The expected result is: " << text << endl;

    cout << "The actual result is:";
    str2.print();

    cout << "The expected result is: " << text << endl;

    cout << "The actual result is:";
    str3.print();
    cout << endl;
}
int main() {
    test1();
    test2();
    test3();
    system("pause");
    return 0;
}