編程題＃1
來源: POJ (Coursera聲明：在POJ上完成的習題將不會計入Coursera的最后成績。)
注意： 總時間限制: 1000ms 內存限制: 65536kB
描述
寫一個MyString 類，使得下面程序的輸出結果是：
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-
解答：
1 #include<iostream> 2 #include<cstring> 3 #include<cstdlib> 4 using namespace std; 5 6 class MyString 7 { 8 public: 9 MyString() { sValue = ""; }; 10 MyString(const char *s) { 11 int n = strlen(s); 12 sValue = new char[n + 1]; 13 int i; 14 for (i = 0; i < n; i++) 15 sValue[i] = s[i]; 16 sValue[i] = '\0'; 17 }; 18 MyString(const string &s) { 19 sValue = new char[strlen(s.c_str()) + 1]; 20 strcpy(sValue, s.c_str()); 21 }; 22 23 MyString operator()(int i, int j) { 24 MyString res; 25 res.sValue = new char[j]; 26 int start=i; 27 int idx = 0; 28 for (idx=0; idx < j; idx++) 29 res.sValue[idx] = sValue[start++]; 30 res.sValue[idx] = '\0'; 31 return res; 32 } 33 char& operator[](int i) { return sValue[i]; } 34 friend ostream& operator<<(ostream &os,const MyString &s) 35 { 36 if (s.sValue == NULL) 37 return os; 38 else 39 { 40 os <<s.sValue; 41 return os; 42 } 43 } 44 friend MyString operator+(const char*str, const MyString &rhs) 45 { 46 MyString res(str); 47 res = res + rhs; 48 return res; 49 } 50 MyString operator+(const MyString &rhs) 51 { 52 MyString res; 53 int n = strlen(sValue) + strlen(rhs.sValue); 54 res.sValue = new char[n]; 55 strcpy(res.sValue, sValue); 56 strcat(res.sValue, rhs.sValue); 57 return res; 58 } 59 MyString operator+(const char *rhs) 60 { 61 MyString res; 62 MyString r(rhs); 63 res = *this + r; 64 return res; 65 } 66 MyString& operator+=(const char *rhs) { 67 MyString res; 68 MyString r(rhs); 69 res = *this + r; 70 *this = res; 71 return *this; 72 } 73 bool operator < (const MyString & rhs) { 74 int flag=strcmp(sValue, rhs.sValue); 75 if (flag == -1) 76 return true; 77 else 78 { 79 return false; 80 } 81 } 82 bool operator > (const MyString & rhs) { 83 int flag = strcmp(sValue, rhs.sValue); 84 if (flag == 1) 85 return true; 86 else 87 { 88 return false; 89 } 90 } 91 bool operator ==(const MyString & rhs) { 92 int flag = strcmp(sValue, rhs.sValue); 93 if (flag == 0) 94 return true; 95 else 96 { 97 return false; 98 } 99 } 100 private: 101 char* sValue; 102 }; 103 104 105 int compareString(const void * e1, const void * e2) 106 { 107 MyString *s1 = (MyString *)e1; 108 MyString *s2 = (MyString *)e2; 109 if (*s1 < *s2) 110 return -1; 111 else if (*s1 == *s2) 112 return 0; 113 else if (*s1>*s2) 114 return 1; 115 } 116 117 int main() 118 { 119 MyString s1("abcd-"), s2, s3("efgh-"), s4(s1); 120 MyString SArray[4] = { "big","me","about","take" }; 121 cout << "1. " << s1 << s2 << s3 << s4 << endl; 122 s4 = s3; s3 = s1 + s3; 123 cout << "2. " << s1 << endl; 124 cout << "3. " << s2 << endl; 125 cout << "4. " << s3 << endl; 126 cout << "5. " << s4 << endl; 127 cout << "6. " << s1[2] << endl; 128 s2 = s1; s1 = "ijkl-"; 129 s1[2] = 'A'; 130 cout << "7. " << s2 << endl; 131 cout << "8. " << s1 << endl; 132 s1 += "mnop"; 133 cout << "9. " << s1 << endl; 134 s4 = "qrst-" + s2; 135 cout << "10. " << s4 << endl; 136 s1 = s2 + s4 + " uvw " + "xyz"; 137 cout << "11. " << s1 << endl; 138 qsort(SArray, 4, sizeof(MyString), compareString); 139 for (int i = 0; i < 4; ++i) 140 cout << SArray[i] << endl; 141 //輸出s1從下標0開始長度為4的子串 142 cout << s1(0, 4) << endl; 143 //輸出s1從下標為5開始長度為10的子串 144 cout << s1(5, 10) << endl; 145 system("pause"); 146 return 0; 147 }