p425.1
1 #include<iostream> 2 #include<cstring> 3 #include<cstdlib> 4 using namespace std; 5 6 class Cow{ 7 char name[20]; 8 char *hobby; 9 double weight; 10 public: 11 Cow(); 12 Cow(const char *nm, const char *ho, double wt); 13 Cow(const Cow &c); 14 ~Cow(); 15 Cow &operator=(const Cow &c); 16 void ShowCow()const; 17 }; 18 19 Cow::Cow(){ 20 strcpy(name, "no body"); 21 hobby = "nothing"; 22 weight = 0.0; 23 } 24 25 Cow::Cow(const char *nm, const char *ho, double wt){ 26 std::strncpy(name, nm, 20); 27 hobby = new char[strlen(ho) + 1]; 28 strcpy(hobby, ho); 29 weight = wt; 30 } 31 32 Cow::Cow(const Cow &c){ 33 hobby = new char[strlen(c.hobby) + 1]; 34 strcpy(hobby, c.hobby); 35 strcpy(name, c.name); 36 weight = c.weight; 37 } 38 39 Cow::~Cow(){ 40 delete[]hobby; 41 } 42 43 Cow & Cow::operator=(const Cow &c){ 44 if (this == &c) 45 return *this; 46 delete[]hobby; 47 hobby = new char[strlen(c.hobby) + 1]; 48 strcpy(hobby, c.hobby); 49 strcpy(name, c.name); 50 weight = c.weight; 51 cout << "hobby " << hobby << endl 52 << "name " << name << endl 53 << "weight " << weight << endl; 54 return *this; 55 } 56 57 void Cow::ShowCow()const{ 58 std::cout << "name is " << name << std::endl 59 << "hobby is " << hobby << std::endl 60 << "weight is " << weight << std::endl; 61 } 62 63 int main(){ 64 Cow test1, test2("Max", "soccer", 6.7); 65 test1.ShowCow(); 66 test2.ShowCow(); 67 Cow test3("Stack", "vollyball", 3.45); 68 cin.get(); 69 test1 = test3; 70 test1.ShowCow(); 71 72 system("pause"); 73 return 0; 74 }
p426.3
1 //头文件： 2 #include<iostream> 3 #include<string> 4 using std::istream; 5 using std::ostream; 6 7 #ifndef STRING2_H_ 8 #define STRING2_H_ 9 class String{ 10 private: 11 char *str; 12 int len; 13 static int num_strings; 14 static const int CINIM = 80; 15 public: 16 String(const char *s); 17 String(); 18 String(const String &); 19 ~String(); 20 int length()const { return len; } 21 String & operator=(const String &); 22 String &operator=(const char*); 23 char&operator[](int i); 24 const char &operator[](int i)const; 25 String & Stringlow(); 26 char * Stringup(); 27 int has(char); 28 friend char * operator+(const String &st1, const String &st2); 29 friend bool operator<(const String &st1, const String &st2); 30 friend bool operator==(const String &st1, const String &st2); 31 friend ostream &operator<<(ostream &os, const String &st); 32 friend istream &operator>>(istream &is, String &st); 33 static int howmany(); 34 }; 35 36 #endif 37 38 //方法： 39 #include<iostream> 40 #include<cctype> 41 #include<cstring> 42 #include<string> 43 #include"String2.h" 44 45 using std::cin; 46 using std::cout; 47 using std::endl; 48 49 int String::num_strings = 0; 50 51 String::String(const char *s){ 52 num_strings++; 53 len = strlen(s); 54 str = new char[len+1]; 55 strcpy(str, s); 56 cout << "num_strings " << num_strings << endl; 57 } 58 59 String::String(){ 60 num_strings++; 61 len = 0; 62 str = NULL; 63 cout << "num_strings " << num_strings << endl; 64 } 65 66 String::String(const String &st){ 67 num_strings++; 68 len = st.len; 69 str = new char[len + 1]; 70 strcpy(str, st.str); 71 cout << "num_strings " << num_strings << endl; 72 } 73 74 String::~String(){ 75 num_strings--; 76 delete[]str; 77 cout << "num_strings " << num_strings << endl; 78 } 79 80 String & String::operator=(const String &st){ 81 if (&st == this) 82 return *this; 83 delete[]str; 84 len = st.len; 85 str = new char[len + 1]; 86 strcpy(str, st.str); 87 return *this; 88 } 89 90 String & String::operator=(const char*s){ 91 delete[]str; 92 len = strlen(s); 93 str = new char[len + 1]; 94 strcpy(str, s); 95 return *this; 96 } 97 98 char & String::operator[](int i){ 99 return str[i]; 100 } 101 102 const char & String::operator[](int i)const{ 103 return str[i]; 104 } 105 106 String & String::Stringlow(){ 107 for (int i = 0; i < len; i++) 108 str[i] = tolower(str[i]); 109 return *this; 110 } 111 112 char * String::Stringup(){ 113 for (int i = 0; i < len; i++) 114 str[i] = toupper(str[i]); 115 return str; 116 } 117 118 int String::has(char ch){ 119 int count = 0; 120 for (int i = 0; i < len; i++) 121 if (str[i] == ch) 122 count++; 123 return count; 124 } 125 126 char * operator+(const String &st1, const String &st2){ 127 char *st3 = new char[st1.len + st2.len+2]; 128 for (int i = 0; i < st1.len; i++) 129 st3[i] = st1[i]; 130 for (int j = 0; j < st2.len; j++) 131 st3[st1.len +1+ j] = st2[j]; 132 st3[st1.len] = ' '; 133 st3[st1.len + st2.len + 1] = '\0'; 134 return st3; 135 } 136 137 bool operator<(const String &st1, const String &st2){ 138 if (strcmp(st1.str, st2.str)) 139 return false; 140 else return true; 141 } 142 143 bool operator==(const String &st1, const String &st2){ 144 if (strcmp(st1.str, st2.str) == 0) 145 return true; 146 else return false; 147 } 148 149 ostream &operator<<(ostream &os, const String &st){ 150 os << "str: " << st.str << endl; 151 return os; 152 } 153 154 istream &operator>>(istream &is, String &st){ 155 char temp[String::CINIM]; 156 is.get(temp, String::CINIM); 157 if (is) 158 st = temp; 159 while (is&&is.get() != '\n') 160 continue; 161 return is; 162 } 163 164 int String::howmany(){ 165 return num_strings; 166 } 167 168 //驱动： 169 #include<iostream> 170 #include<cstdlib> 171 using namespace std; 172 #include "string2.h" 173 174 int main(){ 175 String s1(" and i am a C++ student. "); 176 String s2 = "please enter your name: "; 177 String s3; 178 cout << s2; 179 cin >> s3; 180 s2 = "my name is " + s3; 181 cout << s2 << ".\n"; 182 s2 = s2 + s1; 183 s2.Stringup(); 184 cout << "the string\n" << s2 << "\ncontains " << 185 s2.has('A') << "'A' characters in it.\n"; 186 s1 = "red"; 187 String rgb[3] = { String(s1), String(" green"), String("blue") }; 188 cout << "enter the name of a primary color for mixing light: "; 189 String ans; 190 bool success = false; 191 while (cin >> ans){ 192 ans.Stringlow(); 193 for (int i = 0; i < 3; i++){ 194 if (ans == rgb[i]){ 195 cout << "that's right!\n"; 196 success = true; 197 break; 198 } 199 } 200 if (success) 201 break; 202 else 203 cout << "try again\n"; 204 } 205 cout << "bye\n"; 206 system("pause"); 207 return 0; 208 }