C++ PRIMER PLUS 第六版编程答案（三）

4.13编程练习

1.编写一个C++程序，如下述输出示例所示的那样请求并显示信息：

What is your first name? Beety Sue
What is your last name? Yewe
What letter grade do you deserve? B
What is your age? 22
Name: Yewe, Betty Sue
Grade: C
Age: 22
注意，该程序应该接受的名字包含多个单词。另外，程序将向下调整成绩，即向上调一个字母。假设用户请求A、B或C，所以不必担心D和F之间的空档。

#include <iostream>#include <string>using namespace std;int main(){    string First, Last;    char grade;    int age;    cout << "What is your first name?";    getline(cin, First);    cout << "What is your last name?";    getline(cin, Last);    cout << "What letter grade do you deserve?";    cin >> grade;    cout << "What is your age?";    cin >> age;    cout << "Name: " << Last << "," << First << endl;    cout << "Grade: " << char(grade + 1) << endl;    cout << "Age: " << age << endl;    system("pause");    return 0;}

2. 修改程序清单4.4，使用C++ string类而不是char数组。

#include <iostream>#include <string>using namespace std;int main(){    string s1, s2;    cout << "Enter your name:" << endl;    getline(cin, s1);    cout << "Enter your favorite dessert:" << endl;    getline(cin, s2);    cout << "your name:" << s1 << ",, " << "your favorite dessert:" << s2 << endl;    system("pause");    return 0;}

3.编写一个程序，它要求用户首先输入其名，然后输入其姓；然后程序使用一个逗号和空格将姓和名组合起来，并存储和显示组合结果。请使用char数组和头文件cstring中的函数。下面是该程序运行时的情形：

Enter your first name: Flip
Enter your last name: Fleming
Here's the information in a single string: Fleming , Flip

#include <iostream>#include <cstring>using namespace std;int main(){    char first[10];    char last[10];    cout << "Enter your first name:";    gets(last);    cout << "Enter your last name:";    gets(first);    cout << "Here's the information in a single string: " << first << "," << last << endl;    system("pause");    return 0;}

4.编写一个程序，它要求用户首先输入其名，再输入其姓；然后程序使用一个逗号和空格将姓和名组合起来，并存储和显示组合结果。请使用string对象和头文件string中的函数。下面是该程序运行时的情形：

Enter your first name: Flip
Enter your last name: Fleming
Here's the information in a single string: Fleming , Flip

#include <iostream>#include <string>using namespace std;int main(){    string first, last;    cout << "Enter your first name:";    getline(cin, last);    cout << "Enter your last name:";    getline(cin, first);    cout << "Here's the information in a single string: " << first << "," << last << endl;    system("pause");    return 0;}

5.结构CandyBar包含3个成员。第一个成员存储了糖块的品牌;第二个成员存储糖块的重量（可以有小数）；第三个成员

存储了糖块的卡路里含量（整数）。请编写一个程序，声明这个结构，创建一个名为snack的CandyBar变量，并将其成员分别初始化 为“Mocha Munch”、2.3和350。初始化应在声明snack时进行。最后，程序显示snack变量的内容。

#include <iostream>#include <string>using namespace std;struct CandyBar{    string brand;    float weight;    int caluli;};int main(){    CandyBar* snack = new CandyBar;    snack->brand = "Mocha Munch";    snack->weight = 2.3f;    (*snack).caluli = 350;    cout << snack->brand << endl << snack->weight << endl << snack->caluli << endl;    delete snack;    system("pause");    return 0;}

6. 结构CandyBar包含3个成员，如编程练习5所示。请编写一个程序，创建一个包含3个元素的CandyBar数组，并将它们初始化为所选择的值，然后显示每个结构的内容。

#include <iostream>#include <string>using namespace std;struct CandyBar{    string brand;    float weight;    int caluli;};int main(){    CandyBar snack[3] = {        {"Mocha Munch", 2.3f, 250},        { "Mocha Munch", 2.3f, 250 },        { "Mocha Munch", 2.3f, 250 }    };    cout << snack->brand << endl << (snack+1)->weight << endl << (snack+2)->caluli << endl;    system("pause");    return 0;}

7.William Wingate从事比萨饼分析服务。对于每个披萨饼，他都需要记录下列信息：

披萨饼公司的名称，可以有多个单词组成
披萨饼的直径
披萨饼的质量
请设计一个能够存储这些信息的结构，并编写一个使用这种结构变量的程序。程序将请求用户输入上述信息，然后显示这些息。
请使用cin和cout

#include <iostream>#include <string>using namespace std;struct Pizza{    string name;    float diameter;    float weight;};int main(){    Pizza pizza;    getline(cin, pizza.name);    cin >> pizza.diameter;    cin >> pizza.weight;    cout << pizza.name << endl << pizza.diameter << endl << pizza.weight << endl;    system("pause");    return 0;}

8.完成编程练习7，但使用new来为结构分配内存，而不是声明一个结构变量。另外，让程序在请求输入比萨饼公司名称之前输入比萨饼的直径。

#include <iostream>#include <string>using namespace std;struct Pizza{    string name;    float diameter;    float weight;};int main(){    Pizza* pizza = new Pizza;    cin >> pizza->diameter;    cin.get();  //回车    getline(cin, pizza->name);    cin >> pizza->weight;    cout << pizza->name << endl << pizza->diameter << endl << pizza->weight << endl;    delete pizza;    system("pause");    return 0;}

9.完成编程练习6，但是用new来动态分配数组，而不是声明一个包含3个元素的CandyBar数组。

#include <iostream>#include <string>using namespace std;struct CandyBar{    string brand;    float weight;    int caluli;};int main(){    CandyBar* snack = new CandyBar[3];    snack->brand = "Mocha Munch";    snack->weight = 2.3f;    snack->caluli = 250;    (snack + 1)->brand = "Mocha Munch";    (snack + 1)->weight = 2.3f;    (*(snack + 1)).caluli = 250;    snack[2].brand = "Mocha Munch";    snack[2].weight = 2.3f;    snack[2].caluli = 250;    cout << snack->brand << endl << (snack+1)->weight << endl << (snack+2)->caluli << endl;    delete []snack;    system("pause");    return 0;}

10.编写一个程序，让用户输入三次40码跑的成绩（如果您愿意，也可让用户输入40米跑的成绩）。并显示次数和平均 成绩。请使用一个array对象来存储数据（如果编译器不支持array类，请使用数组）

#include <iostream>#include <string>using namespace std;int main(){    float grade[3];    cin >> grade[0]>>grade[1]>>grade[2];    cout << (grade[0] + grade[1] + grade[2]) / 3 << endl;    system("pause");    return 0;}