c++primer 第l六章编程练习答案

6.11.1

#include<iostream>
#include<cctype>

int main() {
    using namespace std;
    char ch;
    cin.get(ch);
    while (ch != '@') {
        if (isdigit(ch))
            cout << ch;
        else if (isupper(ch)) {
            ch = tolower(ch);
            cout << ch;
        }
        else if (islower(ch)) {
            ch = toupper(ch);
            cout << ch;
        }
        cin.get(ch);
    }
}

6.11.2

#include<iostream>
#include<cctype>

int main() {
    using namespace std;
    double donations[10];
    double donation;
    double average, sum = 0;
    int i, num=0;
    cout << "input donation,at most 10
";
    for (i = 0; (cin >> donation) && (i < 10); i++) {
        donations[i] = donation;
        sum += donations[i];
    }
    average = sum / i;
    for (i = 0; i < 10; i++) {
        if (donations[i] > average)
            num++;
    }
    cout << "average is " << average << " and " << num << " numbers bigger than avergae.";
}

6.11.3

#include<iostream>

int main() {
    using namespace std;
    char ch;
    cout << "Please enter one of the following choices:
"
        "c) carnivore             p) pianist
"
        "t) tree                  g) game
";
    cout << "Please enter a c,p,t,or g:";
    cin >> ch;
    //cout << "A maple is a ";
    while (ch!='f') {
        switch (ch)
        {
        case'c':cout << "A maple is a carnivore.";
            break;
        case'p':cout << "A maple is a pianist.";
            break;
        case't':cout << "A maple is a tree.";
            break;
        case'g':cout << "A maple is a game.";
            break;
        default:cout << "Please enter a c,p,t,or g:";
        }
        cin >> ch;
    }
}

6.11.4

#include<iostream>

using namespace std;

const int strsize = 20;
const int memberSize = 3;

struct bop {
    char fullname[strsize];
    char title[strsize];
    char bopname[strsize];
    int preference;
};
void name(bop *member);
void title(bop *member);
void bopname(bop *menber);
void preference(bop *member);

int main() {
    char choose;
    bop member[3] = {
        {"zhang","manager","boss",1},
        {"li","programer","pg",0},
        {"wang","teacher","tc",2}
    };
    cout << "Benevolent Order of Programmers Report
"
        "a.display by name          b.display by title
"
        "c.display by bopname       d.display by preference
"
        "q.quit
"
        "Enter your choice: ";
    cin >> choose;

    while (choose!='q')
    {
        switch (choose)
        {
        case 'a':name(member);
            break;
        case 'b':title(member);
            break;
        case 'c':bopname(member);
            break;
        case 'd':preference(member);
            break;
        default:cout << "Not good choose
";
            break;
        }
        cout << "Next choose:";
        cin >> choose;
    }
}

void name(bop * member)
{
    for (int i = 0; i < memberSize; i++) {
        cout << member[i].fullname << endl;
    }
}

void title(bop * member)
{
    for (int i = 0; i < memberSize; i++) {
        cout << member[i].title << endl;
    }
}

void bopname(bop * member)
{
    for (int i = 0; i < memberSize; i++) {
        cout << member[i].bopname << endl;
    }
}

void preference(bop * member)
{
    for (int i = 0; i < memberSize; i++) {
        switch (member[i].preference)
        {
        case 0:cout << member[i].fullname << endl;
            break;
        case 1:cout << member[i].title << endl;
            break;
        case 2:cout << member[i].bopname << endl;
            break;
        default:
            cout << "存在非法的偏好";
            break;
        }
    }
}

6.11.5

#include<iostream>

int main() {
    using namespace std;
    int money;
    double tax = 0;
    cout << "Please input your income: ";
    cin >> money;
    cout << fixed;
    cout.precision(2);
    cout.setf(ios::showpoint);
    while (cin.good()&&(money>=0))
    {
        if (money<=5000)
        {
            tax = 0.0;
            break;
        }
        else if ((money > 5000) && (money <= 15000)) {
            tax = (money - 5000)*0.1;
            break;
        }
        else if ((money > 15000) && (money <= 35000)) {
            tax = (money - 15000)*0.15 + 10000 * 0.1;
            break;
        }
        else {
            tax = (money - 35000)*0.2 + 20000 * 0.15 + 10000 * 0.1;
            break;
        }
    }
    cout << "Your personal income tax is " << tax << " tvarps";
}

6.11.6

#include<iostream>
#include<string>

using namespace std;

struct donations
{
    string name;
    double money;
};

int main() {
    int donorSize, grand_patron_size = 0, patrons_size = 0;
    cout << "How many people donate？
"
        "donorSize: ";
    cin >> donorSize;
    donations *donor = new donations[donorSize];
    donations *grand_patrons = new donations[donorSize];
    donations *patrons = new donations[donorSize];
    cout << "Please enter donor's contribution amount:" << endl;
    cout << fixed;
    cout.precision(2);
    cout.setf(ios_base::showpoint);
    for (int i = 0; i < donorSize; i++)
    {
        cout << "name:";
        cin >> donor[i].name;
        //cin.get();
        //cout << "	";
        cout << "contribution amout:";
        cin >> donor[i].money;
    }
    for (int i = 0; i < donorSize; i++)
    {
        if (donor[i].money > 10000) {
            grand_patrons[grand_patron_size] = donor[i];
            ++grand_patron_size;
        }
        else {
            patrons[patrons_size] = donor[i];
            ++patrons_size;
        }
    }
    cout << "=============== Grand Partrons ================" << endl;
    if (grand_patron_size != 0) {
        for (int i = 0; i < grand_patron_size; i++)
        {
            cout << "name: " << grand_patrons[i].name << "	money:" << grand_patrons[i].money << endl;
        }
    }
    else
    {
        cout << "None";
    }
    cout << "================= Partrons ====================" << endl;
    if (patrons_size != 0) {
        for (int i = 0; i < patrons_size; i++)
        {
            cout << "name: " << patrons[i].name << "	money:" << patrons[i].money << endl;
        }
    }
    else
    {
        cout << "None";
    }
    delete[] donor;
    delete[] grand_patrons;
    delete[] patrons;
}

6.11.7

#include<iostream>
#include<string>
#include<cctype>

int main() {
    using namespace std;
    int vowel = 0, consonant = 0, other = 0;
    string word;
    cout << "Enter word (q to quit): 
";
    cin >> word;
    while (cin.good() && word != "q")
    {
        if (isalpha(word[0])) {
            switch (word[0])
            {
            case 'a':
                vowel++;
                break;
            case 'A':
                vowel++;
                break;
            case 'e':
                vowel++;
                break;
            case 'E':
                vowel++;
                break;
            case 'i':
                vowel++;
                break;
            case 'I':
                vowel++;
                break;
            case 'o':
                vowel++;
                break;
            case 'O':
                vowel++;
                break;
            case 'u':
                vowel++;
                break;
            case 'U':
                vowel++;
                break;
            default:
                consonant++;
            }
        }
        else
            other++;
        cin >> word;
    }
    cout << vowel << " words beginning with vowels." << endl;
    cout << consonant << " words beginning with consonants." << endl;
    cout << other << " others.";
}

6.11.8

#include<iostream>
#include<fstream>
#include<cstdlib>
#include<string>

int main() {
using namespace std;
ifstream infile;
string str;
int sum = 0;
infile.open("D:\visual studio 2015\Projects\homework\homework\Debug\TextFile1.txt");
if (infile.is_open()) {
while (infile.good())
{
str += infile.get();
++sum;
}
cout << "The file contains " << sum << " characters.";
}
else
{
cout << "Failed to read file.";
exit(EXIT_FAILURE);
}
infile.close();
}

6.11.9

#include<iostream>
#include<string>
#include<fstream>
#include<cstdlib>

using namespace std;

struct donations
{
string name;
double money;
};

int main() {
    int donorSize, grand_patron_size = 0, patrons_size = 0;
    string donor_information;
    ifstream infile;
    infile.open("D:\visual studio 2015\Projects\homework\homework\TextFile2.txt");
    if (infile.is_open()) {
        infile >> donorSize;
        infile.get();
        cout << donorSize << endl;
        donations *donor = new donations[donorSize];
        donations *grand_patrons = new donations[donorSize];
        donations *patrons = new donations[donorSize];

        cout << fixed;
        cout.precision(2);
        cout.setf(ios_base::showpoint);

        for (int i = 0; i < donorSize; i++)
        {

            getline(infile, donor[i].name);
            infile >> donor[i].money;
            infile.get();
        }
        for (int i = 0; i < donorSize; i++)
        {
            cout << donor[i].name << endl;
            cout << donor[i].money << endl;
        }
        for (int i = 0; i < donorSize; i++)
        {
            if (donor[i].money > 10000) {
                grand_patrons[grand_patron_size] = donor[i];
                ++grand_patron_size;
            }
            else {
                patrons[patrons_size] = donor[i];
                ++patrons_size;
            }
        }
        cout << "=============== Grand Partrons ================" << endl;
        if (grand_patron_size != 0) {
            for (int i = 0; i < grand_patron_size; i++)
            {
                cout << "name: " << grand_patrons[i].name << "	money:" << grand_patrons[i].money << endl;
            }
        }
        else
        {
            cout << "None";
        }
        cout << "================= Partrons ====================" << endl;
        if (patrons_size != 0) {
            for (int i = 0; i < patrons_size; i++)
            {
                cout << "name: " << patrons[i].name << "	money:" << patrons[i].money << endl;
            }
        }
        else
        {
            cout << "None";
        }
        delete[] donor;
        delete[] grand_patrons;
        delete[] patrons;
    }
    else
    {
        cout << "Failed to open file.";
        exit(EXIT_FAILURE);
    }
    infile.close();
}