编程题#6 MyString 求大神解答

题目来自coursera
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.

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-

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-

我的代码：不知道为什么到11行结束就运行出错，被迫中止了，求大神解答

#include <cstring>#include <cstdlib>#include <string>#include <iostream>using namespace std;// 在此处补充你的代码class MyString{private :string str;public://2.三种构造函数MyString() :str(""){}//MyString(const char* str) :str(str){}//本来就没想写这句，ideonline上说数组的哪一行110，有错，char[4]不能转为myatring//但是写了反而多了个error：125行s4=等号出错，对应多个，不懂MyString(string s) :str(s){}MyString(const MyString & s) :str(s.str){}//1.重载<、==、>friend bool operator <(const MyString & a, const MyString &b){if (a.str.length()>b.str.length())return false;string::const_iterator it1 = a.str.begin(),it2=b.str.begin();for (; it1 != a.str.end(); it1++,it2++){if ((*it1) < (*it2))return true;}return false;}friend bool operator ==(const MyString & a, const MyString &b){if (a.str.compare(b.str) == 0){ return true; }return false;}friend bool operator >(const MyString & a, const MyString &b){if (a.str.compare(b.str) > 0){ return true; }return false;}//3.<<friend ostream & operator << (ostream & out,const MyString & s){out << s.str;return out;}//4.[] char & operator [](int i){ return str.at(i);}//6.() string   operator()(int a, int b){ return str.substr(a, b); } //7.+ string operator+(const MyString &s){ return str + s.str; } void operator+=(string s){ str += s; } friend string operator+(string s, const MyString &b){ return s + b.str; } //8.= void operator=(string s){ str = s; }};int CompareString(const void * e1, const void * e2){MyString * s1 = (MyString *)e1;MyString * s2 = (MyString *)e2;if (*s1 < *s2)//1.重载> == <return -1;else if (*s1 == *s2)return 0;else if (*s1 > *s2)return 1;}int main(){MyString s1("abcd-"), s2, s3("efgh-"), s4(s1);//2.两种构造函数MyString SArray[4] = { "big", "me", "about", "take" };cout << "1. " << s1 << s2 << s3 << s4 << endl;s4 = s3;s3 = s1 + s3;//5.+cout << "2. " << s1 << endl;//3.重载<<cout << "3. " << s2 << endl;cout << "4. " << s3 << endl;cout << "5. " << s4 << endl;cout << "6. " << s1[2] << endl;//4.重载[]s2 = s1;s1 = "ijkl-";//5.=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;//6.（）//s1的从下标5开始长度为10的子串cout << s1(5, 10) << endl;return 0;}