C++ Primer Plus | chapter 6 课后编程练习

第六章 分支语句和逻辑运算符

#include<iostream>
#include<cctype>
using namespace std;
int main()
{
    
    
    char ch;
    cin.get(ch);
    while(ch != '@')
    {
    
    
        if(islower(ch)) ch = toupper(ch);
        if(!isdigit(ch))    cout << ch;
        cin.get(ch);
    }
    return 0;
}

#include<iostream>
#include<cctype>
using namespace std;
int main()
{
    
    
    double arr[10];
    double sum = 0.0;
    int cnt = 0, ans = 0;
    while(cnt < 10 && cin >> arr[cnt])  //不同类型的输入会返回false
    {
    
    
        sum += arr[cnt];
        cnt++;
    }
    double avg = sum/cnt;
    for(int i=0; i<cnt; i++)
    {
    
    
        if(arr[i] > avg)    ans++;
    }
    cout << "Avg = " << sum/cnt << "\nCount = " << cnt << "\nThe number of those bigger than avg = " << ans << endl;
    return 0;
}

#include<iostream>
using namespace std;
int main()
{
    
    
    char choice;
    cout << "Please enter one of the following choices:" << endl;
    cout << "c) carnivore\tp) pianist\n" << "t) tree\t\tg) game" << endl;
    do
    {
    
    
        cin >> choice;
        switch(choice)
        {
    
    
            case 'c': cout << "I am not a carnivore." << endl; break;
            case 'p': cout << "He wants to be a pianist" << endl; break;
            case 't': cout << "A maple is a tree" << endl; break;
            case 'g': cout << "This is a game" << endl; break;
            default: cout << "Please enter a c, p, t, or g: ";
        }
    }while(choice != 'c' && choice != 'p' && choice != 't' && choice != 'g');
    return 0;
}

#include<iostream>
using namespace std;
const int strsize = 30;
struct bop
{
    
    
    char fullname[strsize];
    char title[strsize];
    char bopname[strsize];
    int preference;
};
int main()
{
    
    
    bop All[2] =
    {
    
    
        {
    
    
            "aaaa",
            "AAAA",
            "1111",
            0
        },
        {
    
    
            "bbbb",
            "BBBB",
            "2222",
            2
        }
    };
    char ch;
    cout << "Benevolent Order of Programmers Report" << endl;
    cout << "a. display by name\tb.display by title\nc.display by bopname\td.display by preference\nq.quit" << endl;
    cout << "Enter your choice: ";
    while(cin >> ch)
    {
    
    
        switch(ch)
        {
    
    
            case 'a':
                {
    
    
                    for(int i=0; i<2; i++)  cout << All[i].fullname << endl;
                    break;
                }
            case 'b':
                {
    
    
                    for(int i=0; i<2; i++)  cout << All[i].title << endl;
                    break;
                }
            case 'c':
                {
    
    
                    for(int i=0; i<2; i++)  cout << All[i].bopname << endl;
                    break;
                }
            case 'd':
                {
    
    
                    for(int i=0; i<2; i++)
                    {
    
    
                        switch(All[i].preference)
                        {
    
    
                            case 0: cout << All[i].fullname << endl; break;
                            case 1: cout << All[i].title << endl; break;
                            case 2: cout << All[i].bopname << endl; break;
                            default: cout << "Wrong Preference" << endl; break;
                        }

                    }
                    break;
                }
            case 'q': cout << "Bye!" << endl; break;
            default: cout << "Wrong input." << endl; break;
        }
        if(ch == 'q')   break;
        else cout << "Next choice: ";
    }
    return 0;
}

#include<iostream>
using namespace std;
int main()
{
    
    
    double income, ans;
    cout << "Please enter your income: ";
    while(cin >> income && income >= 0)
    {
    
    
        ans = 0;
        if(income > 5000)   (income <= 15000) ? ans += 0.1*(income-5000) : ans += 0.1*10000;
        if(income > 15000)  (income <= 35000) ? ans += 0.15*(income-15000) : ans += 0.15*20000;
        if(income > 35000)  ans += 0.2*(income-35000);
        cout << "Tax: " << ans << endl;
        cout << "Please enter your income: ";
    }
    return 0;
}

#include<iostream>
#include<string>
using namespace std;
struct Donation
{
    
    
    string name;
    double money;
};
int main()
{
    
    
    int n;
    int cntGrand = 0, cntPat = 0;
    cout << "The number of donors: ";
    cin >> n;
    Donation* all = new Donation [n];
    for(int i=0; i<n; i++)
    {
    
    
        cout << "Name: ";
        cin.get();
        getline(cin, all[i].name);
        cout << "Money: ";
        cin >> all[i].money;
    }
    cout << "Grand Patrons: " << endl;
    for(int i=0; i<n; i++)
    {
    
    
        if(all[i].money > 10000)
        {
    
    
            cout << all[i].name << "\n" << all[i].money << endl;
            cntGrand++;
        }
        else cntPat++;
    }
    if(cntGrand == 0)   cout << "none" << endl;
    cout << "Patrons: " << endl;
    for(int i=0; i<n; i++)
        if(all[i].money < 10000)    cout << all[i].name << "\n" << all[i].money << endl;
    return 0;
}

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

int main()
{
    
    
    char words[50];
    int vow = 0, con = 0, other = 0;
    cout << "Enter words: (q to quit)" << endl;
    cin >> words;
    while(strcmp(words, "q") != 0)
    {
    
    
        if(words[0] == 'a' || words[0] == 'e' || words[0] == 'i' || words[0] == 'o' || words[0] == 'u') vow++;
        else con++;
        for(int i=0; i<strlen(words); i++)
        {
    
    
            if(!isalpha(words[i]) && !ispunct(words[i]))
            {
    
    
                other++;
                if(words[0] == 'a' || words[0] == 'e' || words[0] == 'i' || words[0] == 'o' || words[0] == 'u') vow--;
                else con--;
                break;
            }
        }
        cin >> words;
    }
    cout << vow << " words beginning with vowels\n" << con << " words beginning with consonants.\n" << other << " others" << endl;
}

#include<iostream>
#include<fstream>
#include<string>
using namespace std;
int main()
{
    
    
    string filename;
    ifstream inFile;
    cout << "Enter name of data file: ";
    getline(cin, filename);
    inFile.open(filename);
    int cnt = 0;
    char ch;
    if(!inFile.is_open())
    {
    
    
        cout << "Could not open the file " << filename << endl;
        cout << "Program terminating.\n" << endl;
        exit(EXIT_FAILURE);
    }
    inFile >> ch;
    while(inFile.good())
    {
    
    
        cnt++;
        inFile >> ch;
    }
    if(inFile.eof())    cout << "End of file reached.\n";
    else if(inFile.fail())  cout << "Input terminated by data mismatch.\n";
    else cout << "Input terminated for unknown reason.\n";
    cout << "The number of characters: " << cnt << endl;
    inFile.close();
    return 0;
}

#include<iostream>
#include<string>
#include<fstream>
using namespace std;
struct Donation
{
    
    
    string name;
    double money;
};
int main()
{
    
    
    int n;
    int cntGrand = 0, cntPat = 0;
    ifstream inFile;
    string filename;
    cout << "The file's name: ";
    cin >> filename;
    inFile.open(filename);
    inFile >> n;
    Donation* all = new Donation [n];
    for(int i=0; i<n; i++)
    {
    
    
        inFile.get();
        getline(inFile, all[i].name);
        inFile >> all[i].money;
    }
    cout << "Grand Patrons: " << endl;
    for(int i=0; i<n; i++)
    {
    
    
        if(all[i].money > 10000)
        {
    
    
            cout << all[i].name << "\n" << all[i].money << endl;
            cntGrand++;
        }
        else cntPat++;
    }
    if(cntGrand == 0)   cout << "none" << endl;
    cout << "Patrons: " << endl;
    for(int i=0; i<n; i++)
        if(all[i].money < 10000)    cout << all[i].name << "\n" << all[i].money << endl;
    return 0;
}