一、复习题
3.
#include<iostream>
using namespace std; void main()
{
char ch;
int c1, c2;
c1 = c2 = ; 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 = ;
void main()
{
double donation[], sum = 0.0,average;
int i,count=;
for (i = ; 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 == )
return;
else
average = sum / i;
for (int j = ; 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:\n"
<< "a) carnivore\t" << "b) pianist\n"
<< "c) tree\t\t" << "d) game\n";
} void main()
{
showA();
char ch;
cin >> ch;
int flag = ;
while ()
{
switch (ch)
{
case 'a':cout << "A maple is a carnivore." << endl;
flag = ;
break;
case 'b':cout << "A maple is a pianist." << endl;
flag = ;
break;
case 'c':cout << "A maple is a tree." << endl;
flag = ;
break;
case 'd':cout << "A maple is a game." << endl;
flag = ;
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 = ,num=;
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\n"
<< "a. display by name\t" << "b. display by title\n"
<< "c. display by bopname\t"<< "d. display by preference\n"
<< "q. quit\n";
} void main()
{
bop p[num] = {
{ "王一","程序员","first", },
{ "张二", "老师", "2nd", },
{ "李三", "公务员", "3rd", },
{ "赵四", "咨询师", "4th", },
{ "南宫五", "理发师", "5th", },
{ "龙六", "玩家", "6th", }
};
char ch;
show();
int flag = ;
cout << "Enter your choice:";
int l = sizeof(p)/sizeof(p[]);
while (cin>>ch)
{
switch (ch)
{
case 'a':
for (int i = ; i < num&&strlen(p[i].fullname) != ; i++)
cout << p[i].fullname << endl;
break;
case 'b':
for (int i = ; i < num&&strlen(p[i].fullname) != ; i++)
cout << p[i].title << endl;
break;
case 'c':
for (int i = ; i < num&&strlen(p[i].fullname) != ; i++)
cout << p[i].bopname << endl;
break;
case 'd':
for (int i = ; i < num&&strlen(p[i].fullname) != ; i++)
{
switch (p[i].preference)
{
case :cout << p[i].fullname << endl;
break;
case :cout << p[i].title << endl;
break;
case :cout << p[i].bopname << endl;
break;
}
}
break;
case 'q':
flag = ;
cout << "Bye!\n";
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 < )
break;
else if (money <= )
cout << "不交税" << endl;
else if (money <= )
cout << (money - )*0.1 << endl;
else if (money <= )
cout <<*0.1+(money - )*0.15 << endl;
else
cout << * 0.1 +*0.15+ (money - )*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[] = { };
donation *p = new donation[num]; for (int i = ; i < num; i++)
{
cout << "请输入第" << (i + ) << "个捐献者的姓名：";
cin >> p[i].name;
cout << "请输入第" << (i + ) << "个捐献者的捐款数额：";
cin >> p[i].money;
}
int flag = ;//标示，判断是否打印“none”
cout << "重要捐款人如下：" << endl;
for (int i = ; i < num; i++)
{
if (p[i].money > )
{
cout << p[i].name << "捐款" << p[i].money << "元" << endl;
flag = ;
}
}
if (flag == )
cout << "none" << endl;
flag = ;
cout << "其他捐款人如下：" << endl;
for (int i = ; i < num; i++)
{
if (p[i].money <= )
{
cout << p[i].name << "捐款" << p[i].money << "元" << endl;
flag = ;
}
}
if (flag == )
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 = , consonant = , other = , flag = ;
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 = ; break;
case 'e':
case 'E':
vowel++;
flag = ; break;
case 'i':
case 'I':
vowel++;
flag = ; break;
case 'o':
case 'O':
vowel++;
flag = ; break;
case 'u':
case 'U':
vowel++;
flag = ; break;
default:
consonant++;
flag = ; 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 = ;
else {
if (flag)
{
other++;
flag = ;
}
}
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 = ; 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 = ;
inFile >> num;
inFile.get();//抵消换行
donation *p = new donation[num];
for (int i = ; i < num; i++)
{
getline(inFile, p[i].name);
inFile >> p[i].money;
inFile.get();//抵消换行
} int flag = ;//标示，判断是否打印“none”
cout << "重要捐款人如下：" << endl;
for (int i = ; i < num; i++)
{
if (p[i].money > )
{
cout << p[i].name << "捐款" << p[i].money << "元" << endl;
flag = ;
}
}
if (flag == )
cout << "none" << endl;
flag = ;
cout << "其他捐款人如下：" << endl;
for (int i = ; i < num; i++)
{
if (p[i].money <= )
{
cout << p[i].name << "捐款" << p[i].money << "元" << endl;
flag = ;
}
}
if (flag == )
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");
}