一、复习题
3.
#include<iostream> using namespace std; void main() { char ch; int c1, c2; c1 = c2 = 0; while ((ch=cin.get())!='$') { cout << ch; c1++; if (ch = '$') //注意是=，不是== c2++; cout << ch; } cout << "c1=" << c1 << ",c2=" << c2 << endl; system("pause"); }
二、编程练习
1. 编写一个小程序，读取键盘输入，直到遇到@符号为止，并回显输入（除数字外），同时将大写字符转换为小写字符，将小写字符转换为大写（别忘了cctype函数系列）
#include<iostream> #include<cctype> using namespace std; void main() { char ch; while ((ch = cin.get()) && ch != '@') { if (!isdigit(ch)) { if (islower(ch)) //如果是小写字符 ch = toupper(ch);//转化为大写 else if (isupper(ch)) ch = tolower(ch); cout << ch; } } system("pause"); }
2. 编写一个程序，最多将10个donation值读到一个double数组中。程序遇到非数字输入时将结束输入，并报告这些数字的平均值以及数组中有多少个数字大于平均值。
#include<iostream> using namespace std; const int SIZE = 10; void main() { double donation[10], sum = 0.0,average; int i,count=0; for (i = 0; i < SIZE; i++) { if (cin >> donation[i]) sum += donation[i]; else break;//退出最近的循环，即退出for循环 } if (i == 0) return; else average = sum / i; for (int j = 0; j < i; j++) { if (donation[j] > average) count++; } cout << "average=" << average << "," << count << " numbers bigger than average." << endl; system("pause"); }
3.编写一个菜单驱动程序的雏形。该程序显示一个提供4个选项的菜单——每个选项用一个字母标记。如果用户使用有效选项之外的字母进行响应，程序将提示用户输入一个有效的字母，直到用户这样做为止。然后，该程序使用一条switch语句，根据用户的选择执行一个简单的操作。
#include<iostream> using namespace std; void showA() { cout << "Please enter one of the following choices: " << "a) carnivore " << "b) pianist " << "c) tree " << "d) game "; } void main() { showA(); char ch; cin >> ch; int flag = 0; while (1) { switch (ch) { case 'a':cout << "A maple is a carnivore." << endl; flag = 1; break; case 'b':cout << "A maple is a pianist." << endl; flag = 1; break; case 'c':cout << "A maple is a tree." << endl; flag = 1; break; case 'd':cout << "A maple is a game." << endl; flag = 1; break; default:cout << "Please enter a,b,c,d :"; cin >> ch; } if (flag) break; } system("pause"); }
4. 加入Benevolent Order of Programmer后，在BOP大会上，人们便可以通过加入者的真实姓名、头衔或秘密BOP姓名来了解他，请编写一个程序，可以使用真实姓名、头衔、秘密姓名或成员偏好来列出成员。编写该程序时，请使用下面结构
//Benevolent Order of Programmers name structure
Struct bop
{
char fullname[strsize];
char title[strsize];
char bopname[strsize];
int preference;
};
该程序创建一个由上述结构组成的小型数组，并将其初始化为适当的值，另外，该程序使用一个循环让用户在下面的选项中进行选择：
A. Display by name B. Display by title C. Display by bopname
D. Display by preference Q. quit
#include<iostream> using namespace std; const int strsize = 20,num=10; struct bop { char fullname[strsize]; //真实姓名 char title[strsize]; //头衔 char bopname[strsize]; //秘密姓名 int preference; //偏好，当为0时为fullname,1为title,2为bopname }; void show() { cout<< "Benevolent Order of Programmers Report " << "a. display by name " << "b. display by title " << "c. display by bopname "<< "d. display by preference " << "q. quit "; } void main() { bop p[num] = { { "王一","程序员","first",0 }, { "张二", "老师", "2nd",1 }, { "李三", "公务员", "3rd",2 }, { "赵四", "咨询师", "4th",0 }, { "南宫五", "理发师", "5th",1 }, { "龙六", "玩家", "6th", 2 } }; char ch; show(); int flag = 0; cout << "Enter your choice:"; int l = sizeof(p)/sizeof(p[0]); while (cin>>ch) { switch (ch) { case 'a': for (int i = 0; i < num&&strlen(p[i].fullname) != 0; i++) cout << p[i].fullname << endl; break; case 'b': for (int i = 0; i < num&&strlen(p[i].fullname) != 0; i++) cout << p[i].title << endl; break; case 'c': for (int i = 0; i < num&&strlen(p[i].fullname) != 0; i++) cout << p[i].bopname << endl; break; case 'd': for (int i = 0; i < num&&strlen(p[i].fullname) != 0; i++) { switch (p[i].preference) { case 0:cout << p[i].fullname << endl; break; case 1:cout << p[i].title << endl; break; case 2:cout << p[i].bopname << endl; break; } } break; case 'q': flag = 1; cout << "Bye! "; break; default: cout << "Enter error!"; break; } if (flag) break; cout << "Next choice:"; } system("pause"); }
5.在Ncutronia王国，货币单位是tvarp，收入所得税的计算方式如下：
5000 tvarps:不收税
5001～15000 tvarps: 10%
15001～35000 tvarps: 15%
35000 tvarps以上: 20%
例如，收入为38000 tvarps时，所得税为5000x0.00 + 10000x0.10 + 20000x0.15+3000x0.20，即4600 tvarps。请编写一个程序，使用循环来要求用户输入收入，并报告所得税。当用户输入负数或非数字时，循环将结束。
#include<iostream> using namespace std; void main() { double money; cout << "请输入您的收入："; while (cin>>money) { if (money < 0) break; else if (money <= 5000) cout << "不交税" << endl; else if (money <= 15000) cout << (money - 5000)*0.1 << endl; else if (money <= 35000) cout <<10000*0.1+(money - 15000)*0.15 << endl; else cout << 10000 * 0.1 +20000*0.15+ (money - 35000)*0.2 << endl; cout << "请输入您的收入："; } system("pause"); }
6.编写一个程序，记录捐助给“维护合法权利团体”的资金。该程序要求用户输入捐献者数目，然后要求用户输入每一个捐献者的姓名和款项。这些信息被储存在一个动态分配的结构数组中。每个结构有两个成员：用于储存姓名的字符数组（或string对象）和用来存储款项的double成员。读取所有的数据后，程序将显示所有捐款超过10000的捐款者姓名及其捐款数额。该列表前包含一个标题，指出下面的捐款者是重要捐款人（Grand Patrons）。然后，程序将列出其他的捐款者，该列表要以Patrons开头。如果某种类别没有捐款者，则程序将打印单词“none”。该程序只显示这两种类别，而不进行排序。
#include<iostream> #include<string> using namespace std; struct donation { string name; double money; }; void main() { cout << "请输入捐献者数量："; int num; cin >> num; int s[5] = { 0 }; donation *p = new donation[num]; for (int i = 0; i < num; i++) { cout << "请输入第" << (i + 1) << "个捐献者的姓名："; cin >> p[i].name; cout << "请输入第" << (i + 1) << "个捐献者的捐款数额："; cin >> p[i].money; } int flag = 0;//标示，判断是否打印“none” cout << "重要捐款人如下：" << endl; for (int i = 0; i < num; i++) { if (p[i].money > 10000) { cout << p[i].name << "捐款" << p[i].money << "元" << endl; flag = 1; } } if (flag == 0) cout << "none" << endl; flag = 0; cout << "其他捐款人如下：" << endl; for (int i = 0; i < num; i++) { if (p[i].money <= 10000) { cout << p[i].name << "捐款" << p[i].money << "元" << endl; flag = 1; } } if (flag == 0) cout << "none" << endl; delete p[];//用完new一定要记得delete system("pause"); }
7.编写一个程序，他每次读取一个单词，直到用户只输入q。然后，该程序指出有多少单词以元音打头，有多少个单词以辅音打头，还有多少单词不属于这两类。为此，方法之一是使用isalpha()来区分以字母和其他字符打头的单词，然后对于通过salpha()测试的单词，使用if或switch语句来确定哪些是以元音打头。
#include<iostream> #include<cctype> using namespace std; void main() { cout << "Enter words (q to quit):" << endl; char ch; cin.get(ch); int vowel = 0, consonant = 0, other = 0, flag = 1; while (ch != 'q') { if (isalpha(ch)) {//如果参数是字母，返回true if (flag) { switch (ch) { case 'a': case 'A': vowel++; flag = 0; break; case 'e': case 'E': vowel++; flag = 0; break; case 'i': case 'I': vowel++; flag = 0; break; case 'o': case 'O': vowel++; flag = 0; break; case 'u': case 'U': vowel++; flag = 0; break; default: consonant++; flag = 0; break; } } } else if (isspace(ch) || ispunct(ch))//如果参数是空格、tab、换行等空白字符，或者是标点符号，返回true flag = 1; else { if (flag) { other++; flag = 0; } } cin.get(ch); } cout << vowel << " words beginning with vowels " << endl; cout << consonant << " words beginning with consonants " << endl; cout << other << " others" << endl; system("pause"); }
这是一串有问题的代码，找了半天实在不知道错在哪，先贴在这儿，看以后能发现错误不
8.编写一个程序，它打开一个文件夹，逐个字符的读取该文件，直到到达文件末尾，然后指出该文件中包含多少个字符。
#include<iostream> #include<fstream>//文件IO using namespace std; void main() { ifstream inFile;//声明ifstream对象 inFile.open("1.txt");//关联文件 if (!inFile.is_open())//文件打开失败 { cout << "Could not open the file " << endl; exit(EXIT_FAILURE); } char ch; int count = 0; inFile >> ch; while (inFile.good())//输入正确 { ++count; cout << ch; inFile >> ch; } cout << endl; if (inFile.eof()) cout << "End of file reached." << endl; else if (inFile.fail()) cout << "Input terminated by data misamatch." << endl; else cout << "Input terminated for unknown reason." << endl; cout << "文件包含" << count<<"个字符" << endl; inFile.close(); system("pause"); }
9.完成编程练习6，但从文件中读取所需的信息。该文件的第一项应为捐款人数，余下的内容应为成对的行。在每一对中，第一行为捐款人姓名，第二行为捐款数额。即该文件类似于下面：
4
Sam Stone
2000
Freida Flass
100500
Tammy Tubbs
5000
Rich Raptor
55000
#include<iostream> #include<fstream>//文件IO #include<string> using namespace std; struct donation { string name; double money; }; void main() { ifstream inFile;//声明ifstream对象 inFile.open("1.txt");//关联文件 if (!inFile.is_open())//文件打开失败 { cout << "Could not open the file " << endl; exit(EXIT_FAILURE); } int num, i = 0; inFile >> num; inFile.get();//抵消换行 donation *p = new donation[num]; for (int i = 0; i < num; i++) { getline(inFile, p[i].name); inFile >> p[i].money; inFile.get();//抵消换行 } int flag = 0;//标示，判断是否打印“none” cout << "重要捐款人如下：" << endl; for (int i = 0; i < num; i++) { if (p[i].money > 10000) { cout << p[i].name << "捐款" << p[i].money << "元" << endl; flag = 1; } } if (flag == 0) cout << "none" << endl; flag = 0; cout << "其他捐款人如下：" << endl; for (int i = 0; i < num; i++) { if (p[i].money <= 10000) { cout << p[i].name << "捐款" << p[i].money << "元" << endl; flag = 1; } } if (flag == 0) cout << "none" << endl; if (inFile.eof()) cout << "End of file reached." << endl; else if (inFile.fail()) cout << "Input terminated by data misamatch." << endl; else cout << "Input terminated for unknown reason." << endl; inFile.close(); delete [] p;//用完new一定要记得delete system("pause"); }
