第六章习题摘录

输出为：

并且条件中(ch = “&”)是赋值运算符不是比较运算符，所以ch会被赋值为$然后输出，所以条件永远为true，ct2和ct1是相等的。
cin.get(ch)或cin.get()读取一个字符会读取所有的输入包括，空格和换行符；而cin>>ch会跳过空格和换行符
2.++ch和ch+1得到的数值相同
但++ch的类型为char，将作为字符打印，而ch+1是int类型（因为char和int相加），将作为数字打印

#include<iostream>
#include<cctype>
using namespace std;

int main()
{
    char temp, temp_change;
    cout << "请输入字符：";
    cin >> temp;
    while (temp != '@' )//while ((ch = cin.get()) != '@')
    {  
        if (isdigit(temp))
        {
            cout << "请重新输入：";
            cin >> temp;
            continue;
        }
        else if (temp >= 'a' && temp <= 'z')
            temp_change = toupper(temp);
        else
            temp_change = tolower(temp);
        cout << temp_change << endl;
        cout << "请输入字符：";
        cin >> temp;
    }
    system("pause");
    return 0;
}

运行结果

#include<iostream>
#include<string>
#include<array>
using namespace std;

int main()
{
    double donation[10];//const unsigned int SIZE = 10;
                        //array<double, SIZE> donation;
    int i = 0;
    double averg;
    double sum =0.0;
    int num=0;
    cout << "Please enter less than 10 numbers:";  //cout << "Please enter up to ten double value, Non-digital to exit: " << endl;
    while (i<10 && cin >> donation[i]) {
        sum += donation[i];
        i++;
    }
    averg = sum / i;
    for (int j = 0; j < i; j++)
    {
        if (donation[j] > averg)
        {
            num++;
        }
    }
    cout << "The average value is " << averg << ", and there are " << num << " double value large than agerage value!" << endl;
    system("pause");
    return 0;
}

输出结果

#include<iostream>
#include<string>
using namespace std;

int main()
{
    cout << "Please enter one of the following choices:" << endl;
    cout << "c)carnivorce                    p)pianist" << endl;
    cout << "t)tree                          g)game" << endl;
/*
    cout << "Please enter one of the following choices: " << endl;
    cout.flags(ios::left);制符表左对齐
    cout << setw(20) << "c) carnivore" << "p) pianist" << endl;
    cout << setw(20) << "t) tree" << "g) game" << endl;
setw(int n)是c++中在输出操作中使用的字段宽度设置,设置输出的域宽,n表示字段宽度。只对紧接着的输出有效,紧接着的输出结束后又变回默认的域宽。 当后面紧跟着的输出字段长度小于n的时候,在该字段前面用空格补齐;当输出字段长度大于n时,全部整体输出。
*/
    char letter;
    cin >> letter;
    bool exit = false;//引入布尔值，控制Switch的退出

    while (letter&&exit!=true)
    {
        switch (letter) {
        case 'c':cout << "A maple is a carnivore" << endl;
            exit = true;
            break;
        case 'p':cout << "A maple is a pianist" << endl;
            exit = true;
            break;
        case 't':cout << "A maple is a tree" << endl;
            exit = true;
            break;
        case'g':cout << "A maple is a game" << endl;
            exit = true;
            break;
        default:cout << "Please enter a c,p,t,or g:";
            break;
        }

        cin >> letter;

    }

    system("pause");
    return 0;
}

输出结果

#include<iostream>
#include<string>
using namespace std;

int main()
{
    double income=0.0;
    double tax = 0;
    cout << "Please enter your income:";
    cin >> income;
    while (income >= 0)
    {
        if (income <= 5000)
            tax = 0;
        else if (income > 5000 && income <= 15000)
            tax = 0.10 * (income - 5000);
        else if (income > 15000 && income <= 35000)
            tax = 10000 * 0.10 + (income - 15000) * 0.15;
        else
            tax = 10000 * 0.10 + 20000 * 0.15 + (income - 35000) * 0.20;
        cout << "Your tax is:" << tax;
        cin >> income;
    }
    system("pause");
    return 0;
}

isdigital函数的范围是-1到255
输出结果为

#include<iostream>
#include<string>
using namespace std;

struct inflatable {
    char name[20];
    double money;
};
int main()
{
    int donators;
    cout << "Please enter the number of donators:";
    cin >> donators;
    inflatable* donation = new inflatable[donators];
    for (int i = 0;i < donators;i++) {
        cout << "Please enter the name of donator：";
        cin >> donation[i].name;
        cin.get();
        cout << "Please enter the money of donation：";
        cin >> donation[i].money;
        cin.get();
    }
    cout << "Grand Patrons:" << endl;
    int k = 0;
    int j = 0;
    for (int i = 0;i <donators;i++) {
        if (donation[i].money > 10000) {
            cout << donation[i].name << endl;
            k++;
            }
        }
    if(k==0)
        cout << "none"<<endl;
    cout << "Patrons:" << endl;
    for (int i= 0;i <donators;i++) {
        if (donation[i].money <= 10000) {
            cout << donation[i].name << endl;
            j++;
        }   
    }
    if (j==0)
        cout << "none"<<endl;


    system("pause");
    return 0;
}

输出结果

#include<iostream>
#include<string>
using namespace std;


int main()
{
    string word;
    int vowels = 0;
    int consonants = 0;
    int others = 0;
    cout << "Enter words (q to quit):" << endl;
    while (cin >> word && word != "q") {
        if (isalpha(word[0])) {
            if (word[0] == 'a' || word[0] == 'e' || word[0] == 'i' || word[0] == 'o' || word[0] == 'u')
                vowels++;
            else
                consonants++;
        }
        else
            others++;
    }
    cout << vowels << " words beginning with vowels" << endl;
    cout << consonants << " words beginning with consonants" << endl;
    cout << others << " others" << endl;
    system("pause");
    return 0;
}

输出结果