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

abcd-efgh-abcd-

abcd-

3.

abcd-efgh-

efgh-

c

abcd-

ijAl-

ijAl-mnop

qrst-abcd-

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. c
7. abcd-
8. ijAl-
9. ijAl-mnop
10. qrst-abcd-
11. abcd-qrst-abcd- uvw xyz
about
big
me
take
abcd
qrst-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;
}