C++PrimerPlus中文第六版第5章编程练习答案

1、

#include<iostream>
using namespace std;

int main()
{
    int i, j;
    cout << "Enter two numbers: ";
    cin >> i >> j;
    //cout << "Sum between " << i << " and " << j << " is " << (i + j) * (j - i + 1) / 2 << endl;
    int sum = 0;
    while (i++ <= j)
        sum += i;
    cout << "sum: " << sum << endl;

}

2、

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

int main()
{
    const int ArSize = 100;
    array<long double, ArSize> factorials;
    factorials[1] = factorials[0] = 1;
    for (int i = 2; i < ArSize; i++)
        factorials[i] = factorials[i - 1] * i;
    for (int i = 0; i < ArSize; i++)
        cout << "factorials[" << i << "]=" << factorials[i] << endl;

}

3、

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

int main()
{
    int i, sum = 0;
    cout << "Enter a series of integer; quit when input 0\n";
    cin >> i;
    while (i != 0)
    {
        sum += i;
        cout << "You entered " << i << ", and the sum is: " << sum << endl;
        cin >> i;
    }
    cout << "QUIT\n";
}

4、

#include<iostream>
using namespace std;

int main()
{
    double Daphe = 100.0, Celo = 100.0;
    double totalD = Daphe, totalC = Celo;
    int years = 0;
    while (totalC <= totalD)
    {
        totalD += 0.1 * Daphe;
        totalC *= 1.05;
        years++;
    }
    cout << "After " << years << " years, Celo has $" << totalC << " assets, more than Daphe with $" << totalD << endl;
}

5、

#include<iostream>
using namespace std;

int main()
{
    int sales[12];
    const char* months[12] =
    {
        "January", "February", "March",
        "April", "May", "June",
        "July", "August", "September",
        "October", "November", "December"
    };
    int sum = 0;
    cout << "Enter the books sales each month\n";
    for (int i = 0; i < 12; i++)
    {
        cout << months[i] << ": \t";
        if (strlen(months[i]) < 6)
            cout << "\t";
        cin >> sales[i];
        sum += sales[i];
    }
    cout << "The total sales is: " << sum << endl;
}

6、

#include<iostream>
using namespace std;

int main()
{
    int sales[3][12];
    const char* Months[12] =
    {
        "January", "February", "March",
        "April", "May", "June",
        "July", "August", "September",
        "October", "November", "December"
    };
    int sumEachYear, sumTotal = 0;
    for (int year = 0; year < 3; year++)
    {
        sumEachYear = 0;
        cout << "Enter the books sales each month in the " << year+1<< "th year\n";
        for (int month = 0; month < 12; month++)
        {
            cout << Months[month] << ": \t";
            if (strlen(Months[month]) < 6)
                cout << "\t";
            cin >> sales[year][month];
            sumEachYear += sales[year][month];
        }
        cout << "In the "<<year+1 << "th year, the total sales is: " << sumEachYear << endl;
        sumTotal += sumEachYear;
    }
    cout << "Total sales is " << sumTotal << " for three years\n";
        
}

7、

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

//const int CharSize = 20;
struct car
{
    string make;//char make[CharSize];
    int year;
};

int main()
{
    int n;
    cout << "How many cars do you wish to catalog? ";
    (cin >> n).get();
    car* cars = new car[n];
    for (int i = 0; i < n; i++)
    {
        cout << "Car #" << i + 1 << endl;
        cout << "Please enter the make: ";
        getline(cin, cars[i].make);//cin.getline(cars[i].make, CharSize);
        cout << "Please enter the year made: ";
        (cin >> cars[i].year).get();
    }
    cout << "Here is your collection:\n";
    for (int i = 0; i < n; i++)
        cout << cars[i].year << " " << cars[i].make << endl;
}

8、

#include<iostream>
using namespace std;


const int Size = 20;
int main()
{
    const char* obj = "done";
    char word[Size];
    cout << "Enter words (to stop, type the word done)\n";
    cin >> word;
    int count = 0;
    while (strcmp(word, obj))
    {
        count++;
        cin >> word;
    };
    cout << "You entered " << count << " words\n";
}

9、

#include<iostream>
using namespace std;


const int Size = 20;
int main()
{
    string obj = "done";
    string word;
    cout << "Enter words (to stop, type the word done)\n";
    cin >> word;
    int count = 0;
    while (word != obj)
    {
        count++;
        cin >> word;
    };
    cout << "You entered " << count << " words\n";
}

10、

#include<iostream>
using namespace std;

int main()
{
    int n;
    cout << "Enter number of rows:";
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        string s1(n - i - 1, '.'), s2(i + 1, '*');
        cout << s1 << s2 << endl;
    }
}