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-
1 #include <iostream> 2 #include <cstring> 3 #include <cstdlib> 4 using namespace std; 5 // 在此处补充你的代码 6 class MyString:public string { 7 public: 8 MyString():string(){}; 9 MyString(const char *s):string(s) {}; 10 MyString(const string &s):string(s) {}; 11 MyString operator()(int i, int j) { 12 return this->substr(i,j); 13 } 14 }; 15 int CompareString( const void * e1, const void * e2) { 16 MyString * s1 = (MyString * ) e1; 17 MyString * s2 = (MyString * ) e2; 18 if( *s1 < *s2 ) return -1; 19 else if( *s1 == *s2 ) return 0; 20 else if( *s1 > *s2 ) return 1; 21 } 22 int main() { 23 MyString s1("abcd-"),s2,s3("efgh-"),s4(s1); 24 MyString SArray[4] = {"big","me","about","take"}; 25 cout << "1. " << s1 << s2 << s3<< s4<< endl; 26 s4 = s3; s3 = s1 + s3; 27 cout << "2. " << s1 << endl; 28 cout << "3. " << s2 << endl; 29 cout << "4. " << s3 << endl; 30 cout << "5. " << s4 << endl; 31 cout << "6. " << s1[2] << endl; 32 s2 = s1; s1 = "ijkl-"; 33 s1[2] = 'A' ; 34 cout << "7. " << s2 << endl; 35 cout << "8. " << s1 << endl; 36 s1 += "mnop"; 37 cout << "9. " << s1 << endl; 38 s4 = "qrst-" + s2; 39 cout << "10. " << s4 << endl; 40 s1 = s2 + s4 + " uvw " + "xyz"; 41 cout << "11. " << s1 << endl; 42 qsort(SArray,4,sizeof(MyString), CompareString); 43 for( int i = 0;i < 4;++i ) 44 cout << SArray[i] << endl; 45 //输出s1从下标0开始长度为4的子串 46 cout << s1(0,4) << endl; 47 //输出s1从下标为5开始长度为10的子串 48 cout << s1(5,10) << endl; 49 return 0; 50 }