编程题＃1

来源: POJ (Coursera声明：在POJ上完成的习题将不会计入Coursera的最后成绩。)

注意： 总时间限制: 1000ms 内存限制: 65536kB

描述

写一个MyString 类，使得下面程序的输出结果是：

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-

要求：MyString类必须是从C++的标准类string类派生而来。提示1：如果将程序中所有 "MyString" 用"string" 替换，那么题目的程序中除了最后两条语句编译无法通过外，其他语句都没有问题，而且输出和前面给的结果吻合。也就是说，MyString类对 string类的功能扩充只体现在最后两条语句上面。提示2: string类有一个成员函数 string substr(int start,int length); 能够求从 start位置开始，长度为length的子串

程序：

#include <iostream>

#include <cstring>

#include <cstdlib>

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;

    //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;

}

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-

 #include <iostream>

 #include <cstring>

 #include <cstdlib>

 using namespace std;

 // 在此处补充你的代码

 class MyString:public string {

 public:

     MyString():string(){};

     MyString(const char *s):string(s) {};

     MyString(const string &s):string(s) {};

     MyString operator()(int i, int j) {

         return this->substr(i,j);

     }

 };

 int CompareString( const void * e1, const void * e2) {

     MyString * s1 = (MyString * ) e1;

     MyString * s2 = (MyString * ) e2;

     if( *s1 < *s2 ) return -;

     else if( *s1 == *s2 ) return ;

     else if( *s1 > *s2 ) return ;

 }

 int main() {

     MyString s1("abcd-"),s2,s3("efgh-"),s4(s1);

     MyString SArray[] = {"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[] << endl;

     s2 = s1; s1 = "ijkl-";

     s1[] = '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,,sizeof(MyString), CompareString);

     for( int i = ;i < ;++i )

         cout << SArray[i] << endl;

     //输出s1从下标0开始长度为4的子串

     cout << s1(,) << endl;

     //输出s1从下标为5开始长度为10的子串

     cout << s1(,) << endl;

     return ;

 }