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