【C++ Primer Plus】编程练习答案——第6章

  1 void ch6_1() {
  2     using namespace std;
  3     char ch;
  4     while ((ch = cin.get()) != '@') {
  5         if (isdigit(ch))
  6             continue;
  7         else if (islower(ch))
  8             ch = toupper(ch);
  9         else if (isupper(ch))
 10             ch = tolower(ch);
 11         cout << ch;
 12     }
 13 }
 14
 15 void ch6_2() {
 16     using namespace std;
 17     const unsigned int ArrSize = 10;
 18     double donations[ArrSize]{0};
 19     double average{0};
 20     unsigned int overcount{0};
 21     cout << "enter 10 donations in double: " << endl;
 22     for (int i = 0; i < ArrSize; ++ i) {
 23         while (!(cin >> donations[i])) {
 24             cin.clear();
 25             while (cin.get() != '\n')
 26                 continue;
 27             cout << "must enter a double: ";
 28         }
 29     }
 30     for (int i = 0; i < ArrSize; ++ i)
 31         average += donations[i];
 32     average /= ArrSize;
 33     for (int i = 0; i < ArrSize; ++ i)
 34         if (donations[i] > average)
 35             ++ overcount;
 36     cout << "average donation: " << average << endl;
 37     cout << overcount << " donations above average" << endl;
 38 }
 39
 40 void ch6_3() {
 41     using namespace std;
 42     char ch;
 43     cout << "Please enter one of the following choices: " << endl;
 44     cout << "c) carnivore \t p) pianist" << endl;
 45     cout << "t) tree \t g) game" << endl;
 46     bool loop = true;
 47     while (loop) {
 48         cin >> ch;
 49         switch (ch) {
 50             case 'c':
 51                 cout << "carnivore" << endl;
 52                 loop = false;
 53                 break;
 54             case 'p':
 55                 cout << "pianist" << endl;
 56                 loop = false;
 57                 break;
 58             case 't':
 59                 cout << "tree" << endl;
 60                 loop = false;
 61                 break;
 62             case 'g':
 63                 cout << "game" << endl;
 64                 loop = false;
 65                 break;
 66             default:
 67                 cout << "Please enter a c, p, t, or g: ";
 68                 break;
 69         }
 70     }
 71 }
 72
 73 void ch6_4() {
 74     using namespace std;
 75     const int strsize = 100;
 76     struct bop {
 77         char fullname[strsize];
 78         char title[strsize];
 79         char bopname[strsize];
 80         int preference; // 0 = fullname, 1 = title, 2 = bopname
 81     };
 82     const int ArSize = 3;
 83     bop member[ArSize] = {
 84             {"fullname1", "title1", "bopname1", 3},
 85             {"fullname2", "title2", "bopname2", 2},
 86             {"fullname3", "title3", "bopname3", 1}
 87     };
 88     bool loop = true;
 89     char ch;
 90     cout << "Benevolent Order of Programmers Report" << endl
 91         << "a. display by name \t b. display by title" << endl
 92         << "c. display by bopname \t b. display by preference" << endl
 93         << "q. quit" << endl;
 94     while (loop) {
 95         cout << "Enter your choice: ";
 96         cin >> ch;
 97         switch (ch) {
 98             case 'a':
 99                 for (int i = 0; i < ArSize; ++ i)
100                     cout << member[i].fullname << endl;
101                 break;
102             case 'b':
103                 for (int i = 0; i < ArSize; ++ i)
104                     cout << member[i].title << endl;
105                 break;
106             case 'c':
107                 for (int i = 0; i < ArSize; ++ i)
108                     cout << member[i].bopname << endl;
109                 break;
110             case 'd':
111                 for (int i = 0; i < ArSize; ++ i) {
112                     if (member[i].preference == 1)
113                         cout << member[i].fullname << endl;
114                     else if (member[i].preference == 2)
115                         cout << member[i].title << endl;
116                     else
117                         cout << member[i].bopname << endl;
118                 }
119                 break;
120             case 'q':
121                 loop = false;
122             default:
123                 cout << "enter a, b, c, d, or q: ";
124                 break;
125         }
126     }
127 }
128
129 void ch6_5() {
130     using namespace std;
131     unsigned int salary{0};
132     double tax{0};
133     while (true) {
134         cout << "enter your salary: ";
135         if (!(cin >> salary)) {
136             cout << "invalid input!" << endl;
137             break;
138         }
139         if (salary <= 5000)
140             tax = 0;
141         else if (salary > 5000 && salary <= 15000)
142             tax = (salary - 5000) * 0.1;
143         else if (salary > 15000 && salary <= 35000)
144             tax = 10000 * 0.1 + (salary - 15000) * 0.15;
145         else
146             tax = 10000 * 0.1 + 20000 * 0.15 + (salary - 35000) * 0.2;
147         cout << "tax: " << tax << endl;
148     }
149
150 }
151
152 void ch6_6() {
153     using namespace std;
154     struct donator {
155         string name;
156         double amount;
157     };
158     unsigned int donum{0};
159     cout << "enter number of donators: ";
160     while (!(cin >> donum)) {
161         cin.clear();
162         while (cin.get() != '\n')
163             continue;
164         cout << "enter a number: ";
165     }
166     cin.get();
167     donator * donator_arr = new donator[donum];
168     cout << "enter name and amount for each donator" << endl;
169     for (int i = 0; i < donum; ++ i) {
170         cout << "#" << i + 1 << " name: ";
171         getline(cin, donator_arr[i].name);
172         cout << "#" << i + 1 << " amount: ";
173         while (!(cin >> donator_arr[i].amount)) {
174             cin.clear();
175             while (cin.get() != '\n')
176                 continue;
177             cout << "enter a number: ";
178         }
179         cin.get();
180     }
181     bool grand{false}, normal{false};
182     cout << endl << "Grand Patrons: " << endl;
183     for (int i = 0; i < donum; ++ i)
184         if (donator_arr[i].amount >= 10000) {
185             grand = true;
186             cout << donator_arr[i].name << ": " << donator_arr[i].amount << endl;
187         }
188     if (!grand)
189         cout << "None!" << endl;
190     cout << endl << "Other Patrons: " << endl;
191     for (int i = 0; i < donum; ++ i)
192         if (donator_arr[i].amount < 10000) {
193             normal = true;
194             cout << donator_arr[i].name << ": " << donator_arr[i].amount << endl;
195         }
196     if (!normal)
197         cout << "None!" << endl;
198 }
199
200 void ch6_7() {
201     using namespace std;
202     string word;
203     int vowels{0}, consonant{0}, other{0};
204     cout << "Enter words (q to quit): " << endl;
205     cin >> word;
206     while (word != "q") {
207         if (isalpha(word[0])) {
208             switch (word[0]) {
209                 case 'a':
210                 case 'e':
211                 case 'i':
212                 case 'o':
213                 case 'u':
214                     ++ vowels;
215                     break;
216                 default:
217                     ++ consonant;
218                     break;
219             }
220         }
221         else
222             ++ other;
223         cin >> word;
224     }
225     cout << vowels << " words beginning with vowels" << endl
226         << consonant << " words beginning with consonants" << endl
227         << other << " others" << endl;
228 }
229
230 void ch6_8() {
231     using namespace std;
232     const string FILENAME = "../C++PrimerPlus/testfiles/test.txt";
233     ifstream InFile;
234     InFile.open(FILENAME);
235     if (!InFile.is_open()) {
236         cout << "file not found" << endl;
237         return;
238     }
239     unsigned int count{0};
240     char ch;
241     while ((ch = InFile.get()) != EOF)
242         ++ count;
243     InFile.close();
244     cout << count << " chars in this file" << endl;
245 }
246
247 void ch6_9() {
248     using namespace std;
249     struct donator {
250         string name;
251         double amount;
252     };
253     const string FILENAME = "../C++PrimerPlus/testfiles/patrons.txt";
254     ifstream InFile;
255     InFile.open(FILENAME);
256     if (!InFile.is_open()) {
257         cout << "file not found" << endl;
258         return;
259     }
260     unsigned int donum{0};
261     InFile >> donum; InFile.get();
262     donator * donator_arr = new donator[donum];
263     for (int i = 0; i < donum; ++ i) {
264         getline(InFile, donator_arr[i].name);
265         InFile >> donator_arr[i].amount;
266         InFile.get();
267     }
268     InFile.close();
269     bool grand{false}, normal{false};
270     cout << endl << "Grand Patrons: " << endl;
271     for (int i = 0; i < donum; ++ i)
272         if (donator_arr[i].amount >= 10000) {
273             grand = true;
274             cout << donator_arr[i].name << ": " << donator_arr[i].amount << endl;
275         }
276     if (!grand)
277         cout << "None!" << endl;
278     cout << endl << "Other Patrons: " << endl;
279     for (int i = 0; i < donum; ++ i)
280         if (donator_arr[i].amount < 10000) {
281             normal = true;
282             cout << donator_arr[i].name << ": " << donator_arr[i].amount << endl;
283         }
284     if (!normal)
285         cout << "None!" << endl;
286 }