c++primer 第五章编程练习答案

5.9.1

#include<iostream>
int main() {
    using namespace std;
    int one, two, temp, sum = 0;
    cout << "input first interger: ";
    cin >> one;
    cout << "input second interger: ";
    cin >> two;
    for (temp = one; temp <= two; ++temp)
        sum += temp;
    cout << "Add from " << one << " to " << two << " is " << sum;
}

5.9.2

#include<iostream>
#include<array>

const int ArSize = 16;

int main() {
    using namespace std;
    array<long double, ArSize> factorials;
    factorials[1] = factorials[0] = 1.0;
    for (int i = 2; i < ArSize; i++)
        factorials[i] = i*factorials[i - 1];
    for (int i = 0; i < ArSize; i++)
        cout << i << "! = " << factorials[i] << endl;
}

5.9.3

#include<iostream>

int main() {
    using namespace std;
    int number, sum = 0;
    cout << "Please input interger number,end with 0." << endl;
    cin >> number;
    while (number) {
        sum += number;
        cout << "Now,sum is " << sum << endl;
        cin >> number;
    }
}

5.9.4

#include<iostream>

const double interest_C = 0.05;
const double interest_D = 0.10;

int main() {
    using namespace std;
    double deposit_D, deposit_C;
    deposit_C = deposit_D = 100.0;
    int year = 0;
    do {
        deposit_C *= 1.05;
        deposit_D += (0.1 * 100);
        ++year;
    } while (deposit_C <= deposit_D);
    cout << "deposit_C is " << deposit_C << endl;
    cout << "deposit_D is " << deposit_D << endl;
    cout << year << " years C‘s deposit more than D";
}

5.9.5

#include<iostream>
#include<string>

int main() {
    using namespace std;
    string months[12] = {
        "一月",
        "二月",
        "三月",
        "四月",
        "五月",
        "六月",
        "七月",
        "八月",
        "九月",
        "十月",
        "十一月",
        "十二月",
    };
    int sales[12];
    int sum = 0;
    for (int i = 0; i < 12; ++i) {
        cout << "请输入第" << months[i] << "的销售额: ";
        cin >> sales[i];
    }
    for (int i = 0; i < 12; i++) {
        sum += sales[i];
    }
    cout << "这一年的销售额是：" << sum;
}

5.9.6

#include<iostream>
#include<string>

int main() {
    using namespace std;
    string months[12] = {
        "一月",
        "二月",
        "三月",
        "四月",
        "五月",
        "六月",
        "七月",
        "八月",
        "九月",
        "十月",
        "十一月",
        "十二月",
    };
    int sales[3][12];
    int sum_years[3] = { 0,0,0 };
    int sum = 0;
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 12; j++) {
            cout << "请输入第" << i + 1 << "年," << "第" << months[j] << "的销售额: ";
            cin >> sales[i][j];
        }
    }
    for (int i = 0; i < 3; i++) {
        cout << "第 " << i+1 << " 年销售额为：";
        for (int j = 0; j < 12; j++) {
            sum_years[i] += sales[i][j];
        }
        cout << sum_years[i] << endl;
    }
    cout << "三年的总销售额为：";
    for (int i = 0; i < 3; i++) {
        sum += sum_years[i];
    }
    cout << sum;
}

5.9.7

#include<iostream>
#include<string>

using namespace std;
struct car
{
    string manufacturer;
    int production_date;
};

int main() {
    int car_number;
    cout << "How many cars do you have? ";
    cin >> car_number;
    car *cars = new car[car_number];
    for (int i = 0; i < car_number; i++) {
        cout << "Car # " << i + 1 << endl;
        cout << "Please enter the make: ";
        cin >> cars[i].manufacturer;
        cout << "Please enter the year made: ";
        cin >> cars[i].production_date;
    }
    cout << "Here is your collection:\n";
    for (int i = 0; i < car_number; i++) {
        cout << cars[i].production_date << "\t" << cars[i].manufacturer << endl;
    }
}

5.9.8

#include<iostream>
#include<cstring>

int main() {
    using namespace std;
    char charr[20];
    cout << "Enter words (to stop,type the word done):\n";
    int sum;
    for (sum=0;strcmp(charr,"done");sum++)
    {
        cin >> charr;
    }
    cout << "for sure\n";
    cout << "You enter a total of " << sum-1 << " words";
}

5.9.9

#include<iostream>
#include<string>

int main() {
    using namespace std;
    string charr;
    cout << "Enter words (to stop,type the word done):\n";
    int sum;
    for (sum = 0; charr!="done"; sum++)
    {
        cin >> charr;
    }
    //cout << "for sure\n";
    cout << "You enter a total of " << sum - 1 << " words";
}

5.9.10

#include<iostream>

int main() {
    using namespace std;
    int rows;
    cout << "Enter number of rows: ";
    cin >> rows;
    char **charr = new char*[rows];//开辟行
    for (int i = 0; i < rows; i++)
    {
        *(charr+i) = new char[rows];//开辟列
    }
    for (int i = 0; i < rows; i++) {
        for (int j = rows - 1; j >= 0; j--) {
            if ((j + i) >= 4)
                charr[i][j] = ‘*‘;
            else
                charr[i][j] = ‘.‘;
        }
    }
    for (int i = 0; i < rows; ++i) {
        for (int j = 0; j < rows; ++j)
            cout << charr[i][j];
        cout << endl;
    }
    //cout << charr[2][0];
}