编程题＃6：MyString（C++程序设计第10周）

描述

请写出 MyString类，使得下面程序的输出结果符合下面的要求。

#include <cstring>#include <cstdlib>#include <string>#include <iostream>using namespace std;// 在此处补充你的代码int CompareString( const void * e1, const void * e2){        MyString * s1 = (MyString * ) e1;        MyString * s2 = (MyString * ) e2;        if( * s1 < *s2 )                 return -1;        else if( *s1 == *s2)                 return 0;        else if( *s1 > *s2 )                 return 1;}int main(){        MyString s1("abcd-"),s2,s3("efgh-"),s4(s1);        MyString SArray[4] = {"big","me","about","take"};        cout << "1. " << s1 << s2 << s3<< s4<< endl;        s4 = s3;        s3 = s1 + s3;        cout << "2. " << s1 << endl;        cout << "3. " << s2 << endl;        cout << "4. " << s3 << endl;        cout << "5. " << s4 << endl;        cout << "6. " << s1[2] << endl;        s2 = s1;        s1 = "ijkl-";        s1[2] = 'A' ;        cout << "7. " << s2 << endl;        cout << "8. " << s1 << endl;        s1 += "mnop";        cout << "9. " << s1 << endl;        s4 = "qrst-" + s2;        cout << "10. " << s4 << endl;        s1 = s2 + s4 + " uvw " + "xyz";        cout << "11. " << s1 << endl;        qsort(SArray,4,sizeof(MyString),CompareString);        for( int i = 0;i < 4;i ++ )        cout << SArray[i] << endl;        //s1的从下标0开始长度为4的子串        cout << s1(0,4) << endl;        //s1的从下标5开始长度为10的子串        cout << s1(5,10) << endl;        return 0;}

输入

无

输出

1. abcd-efgh-abcd-

2. abcd-

3.

1. abcd-efgh-

2. efgh-

3. c

4. abcd-

5. ijAl-

6. ijAl-mnop

7. qrst-abcd-

8. abcd-qrst-abcd- uvw xyz

about

big

me

take

abcd

qrst-abcd-

样例输入

无

样例输出

1. abcd-efgh-abcd-2. abcd-3.4. abcd-efgh-5. efgh-6. c7. abcd-8. ijAl-9. ijAl-mnop10. qrst-abcd-11. abcd-qrst-abcd- uvw xyzaboutbigmetakeabcdqrst-abcd-

源码

#include <cstring>#include <cstdlib>#include <string>#include <iostream>using namespace std;// 在此处补充你的代码class MyString : public string{public:    MyString():string() {/*cout << "!";*/};    MyString(const string &str):string(str) {/*cout << "@";*/}; //类型转换构造函数    MyString(const char* str):string(str) {/*cout << "#";*/};//char*是数据类型，而string是类，要弄清楚。    MyString(MyString& myStr):string(myStr) {/*cout << "$";*/};//复制构造函数    /*    我们发现在派生类的拷贝构造函数中的初始化列表中，基类拷贝构造函数的参数是派生类，但是    这样子是没有关系的，编译系统会自动将派生类缩减成基类规模（这是我的个人理解，进行缩减的    只是派生类的临时对象，不会对参数进行修改），然后传入给基类的拷贝构造函数，然后在派生类    的拷贝构造函数当中再将派生类比基类多出的成员变量进行拷贝。       */    MyString operator()(int start, int length)    {//      cout << "%";        return this->substr(start, length);    };};int CompareString( const void * e1, const void * e2) {    MyString * s1 = (MyString * ) e1;    MyString * s2 = (MyString * ) e2;    if( *s1 < *s2 )     return -1;    else if( *s1 == *s2 ) return 0;    else if( *s1 > *s2 ) return 1;}int main() {    MyString s1("abcd-"),s2,s3("efgh-"),s4(s1);    MyString SArray[4] = {"big","me","about","take"};    cout << "1. " << s1 << s2 << s3<< s4<< endl;    s4 = s3;        s3 = s1 + s3;//此处会调用string类型转换构造函数    cout << "2. " << s1 << endl;    cout << "3. " << s2 << endl;    cout << "4. " << s3 << endl;    cout << "5. " << s4 << endl;    cout << "6. " << s1[2] << endl;    s2 = s1;    s1 = "ijkl-";    s1[2] = 'A' ;    cout << "7. " << s2 << endl;    cout << "8. " << s1 << endl;    s1 += "mnop";    cout << "9. " << s1 << endl;    s4 = "qrst-" + s2;//此处会调用string类型转换构造函数    cout << "10. " << s4 << endl;    s1 = s2 + s4 + " uvw " + "xyz";    cout << "11. " << s1 << endl;    qsort(SArray,4,sizeof(MyString), CompareString);    for( int i = 0;i < 4;++i )        cout << SArray[i] << endl;    //输出s1从下标0开始长度为4的子串    cout << s1(0,4) << endl;    //输出s1从下标为5开始长度为10的子串    cout << s1(5,10) << endl;    return 0;}