程设作业：MyString类

直接贴代码：

这个是第一题，直接写的那个。

#include <string.h>#include <stdlib.h>#include <string>#include <iostream>using namespace std;class MyString{public:MyString();MyString(char*);MyString(const MyString&);int getlen() ;char& operator [] (int);char* operator () (int, int);MyString operator += (const char*);friend ostream& operator << (ostream& output, const MyString&);friend MyString operator + (const MyString&, const MyString&);friend bool operator > (MyString&, MyString&);friend bool operator < (MyString&, MyString&);friend bool operator == (MyString&, MyString&);private:char* str;};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的下标为0的字符开始长度为4的子串 cout << s1(0,4) << endl; //输出s1的下标为5的字符开始长度为10的子串 cout << s1(5,10) << endl; }MyString::MyString(){if(str) delete str;str = new char [1];str[0] = 0;}MyString::MyString(char* x_){int len = strlen(x_);if(str) delete str;str = new char [len + 1];strcpy(str, x_);}MyString::MyString(const MyString& x_){int len = strlen(x_.str);if(str) delete str;str = new char [len + 1];strcpy(str, x_.str);}int MyString::getlen(){return strlen(str);}ostream& operator << (ostream& output, const MyString& x_){output << x_.str;return output;}MyString operator + (const MyString& x_, const MyString& y_){int i;MyString res;int lena = strlen(x_.str), lenb = strlen(y_.str);if(res.str) delete res.str;res.str = new char [lena + lenb + 1];for(i = 0; i != lena; ++i){res.str[i] = x_.str[i];}for(i = 0; i != lenb; ++i){res.str[lena + i] = y_.str[i];}res.str[lena + lenb] = 0;return res;}char& MyString::operator [] (int x_){return str[x_];}MyString MyString::operator += (const char* x_){int i;int lena = strlen(str), lenb = strlen(x_);char *tmp = new char [lena + 1];for(i = 0; i != lena; ++i){tmp[i] = str[i];}if(str) delete str;str = new char [lena + lenb + 1];for(i = 0; i != lena; ++i){str[i] = tmp[i];}for(i = 0; i != lenb; ++i){str[lena + i] = x_[i];}str[lena + lenb] = 0;return *this;}char* MyString::operator () (int x_, int y_){int i;char* tmp = new char [y_];for(i = x_; i != x_ + y_; ++i){tmp[i - x_] = str[i];}tmp[y_] = 0;return tmp;}bool operator > (MyString& x_, MyString& y_){int i;int lena = x_.getlen(), lenb = y_.getlen();int len;if(lena < lenb) len = lena;else len = lenb;for(i = 0; i != len; ++i){if(x_.str[i] > y_.str[i]){return true;}if(x_.str[i] < y_.str[i]){return false;}}if(lena < lenb){return true;}return false;}bool operator < (MyString& x_, MyString& y_){if((x_ > y_) || (x_ == y_)){return false;}return true;}bool operator == (MyString& x_, MyString& y_){int i;int lena = x_.getlen(), lenb = y_.getlen();if(lena != lenb){return false;}for(i = 0; i != lena; ++i){if(x_.str[i] != y_.str[i]){return false;}}return true;}

这个是第二题，继承了string类。

#include <string.h>#include <stdlib.h>#include <string>#include <iostream>using namespace std;class MyString : public string{public:MyString() : string() { };MyString(const char* str) : string(str) { };MyString(string str) : string(str) { };MyString operator () (int x_, int y_){return substr(x_, y_);}};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的下标为0的字符开始长度为4的子串 cout << s1(0,4) << endl; //输出s1的下标为5的字符开始长度为10的子串 cout << s1(5,10) << endl; }