C++ Primer Plus 第四章练习题

4.7.1 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_name, last_name;
cout<<"What is your first name? ";
getline(cin, first_name);
cout<<"What is your last name? ";
getline(cin, last_name);
cout<<"What letter grade do you deserve? ";
char grade;
cin>>grade;
cout<<"What is your age? ";
unsigned int age;
cin>>age;
cout<<"Name: "<<last_name<<", "<<first_name<<endl
<<"Grade: "<<(char)(grade+1)<<endl
<<"Age: "<<age<<endl;
return 0;
}

4.7.2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 name, dessert;
cout<<"Enter your name: "<<endl;
getline(cin, name);
cout<<"Enter your favorite dessert: "<<endl;
getline(cin, dessert);
cout<<"I have some delicious "<<dessert;
cout<<" for you, "<<name<<endl;
return 0;
}

4.7.3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()
{
const int ArrSize = 20;
char first_name[ArrSize];
char last_name[ArrSize];
cout<<"Enter your first name: ";
cin.get(first_name, ArrSize).get();
cout<<"Enter your last name: ";
cin.get(last_name, ArrSize).get();
cout<<"Here's the information in a single string: "
<<strcat(strcat(last_name, ", "), first_name)<<endl;
return 0;
}

4.7.4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_name, last_name;
cout<<"Enter your first name: ";
getline(cin, first_name);
cout<<"Enter your last name: ";
getline(cin ,last_name);
cout<<"Here's the information in a single string: "
<<last_name + ", " + first_name<<endl;
return 0;
}

4.7.5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;
double weight;
unsigned int calorie;
};

int main()
{
CandyBar snack = { "Mocha Munch", 2.3, 350 };
cout<<"The snack's brand is: "<<snack.brand<<endl
<<"The snack's weight is: "<<snack.weight<<endl
<<"The snack's calorie is: "<<snack.calorie<<endl;
return 0;
}

4.7.6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;
double weight;
unsigned int calorie;
};

int main()
{
CandyBar snack[3] =
{
{ "Mocha Munch", 2.3, 350 },
{ "Apple Tar", 2.5, 300 },
{ "Orange Too", 2.6, 900 }
};
cout<<"The snack[0]'s brand is: "<<snack[0].brand
<<"  weight is: "<<snack[0].weight
<<"  calorie is: "<<snack[0].calorie<<endl;
cout<<"The snack[1]'s brand is: "<<snack[1].brand
<<"  weight is: "<<snack[1].weight
<<"  calorie is: "<<snack[1].calorie<<endl;
cout<<"The snack[2]'s brand is: "<<snack[2].brand
<<"  weight is: "<<snack[2].weight
<<"  calorie is: "<<snack[2].calorie<<endl;
return 0;
}

4.7.7William 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，然后显示这些信息。请使用cin和cout

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

struct Pizza
{
string company_name;
double diameter;
double weight;
};

int main()
{
Pizza pizza;
cout<<"Please input the pizza's company name: ";
cin>>pizza.company_name;
cout<<"Please input the pizza's diameter: ";
cin>>pizza.diameter;
cout<<"Please input the pizza's weight: ";
cin>>pizza.weight;
cout<<"The pizza's company name is "<<pizza.company_name<<endl
<<"The pizza's diameter is "<<pizza.diameter<<endl
<<"The pizza's weight is "<<pizza.weight<<endl;
return 0;
}

4.7.8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>
using namespace std;

struct Pizza
{
string company_name;
double diameter;
double weight;
};

int main()
{
Pizza *pizza = new Pizza;
cout<<"Please input the pizza's diameter: ";
cin>>pizza->diameter;
cout<<"Please input the pizza's company name: ";
cin>>pizza->company_name;
cout<<"Please input the pizza's weight: ";
cin>>pizza->weight;
cout<<"The pizza's company name is "<<pizza->company_name<<endl
<<"The pizza's diameter is "<<pizza->diameter<<endl
<<"The pizza's weight is "<<pizza->weight<<endl;
delete pizza;
return 0;
}

4.7.9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;
double weight;
unsigned int calorie;
};

int main()
{
CandyBar *snack = new CandyBar[3];
cout<<"The snack[0]'s brand is: "<<snack[0].brand
<<"  weight is: "<<snack[0].weight
<<"  calorie is: "<<snack[0].calorie<<endl;
cout<<"The snack[1]'s brand is: "<<snack[1].brand
<<"  weight is: "<<snack[1].weight
<<"  calorie is: "<<snack[1].calorie<<endl;
cout<<"The snack[2]'s brand is: "<<snack[2].brand
<<"  weight is: "<<snack[2].weight
<<"  calorie is: "<<snack[2].calorie<<endl;
delete [] snack;
return 0;
}

4.7.10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 <array>
using namespace std;

int main()
{
array<double, 3> ai;
double first_score, second_score, third_score;
cout<<"Please input the first score: ";
cin>>first_score;
cout<<"Please input the second score: ";
cin>>second_score;
cout<<"Please input the third score: ";
cin>>third_score;
ai[0] = first_score;    ai[1] = second_score;     ai[2] = third_score;
cout<<"The number of times is: "<<ai.size()<<endl
<<"The average score is: "<<(ai[0] + ai[1] + ai[2]) / 3.0<<endl;
return 0;
}
/*我使用的IDE是codeblocks，我在编译时出现了这个错误：
This file requires compiler and library support for the \ ISO C++ 2011 standard.其实就是说array数组需要C++ 2011 标准。
也就是说编译选项应该选上C++ 2011标准，具体步骤如下：
Settings->Compiler->Compiler Flags ->Check:"Have g++ follow the C++11 ISO C++ language standard"
如果你使用的是其他IDE或者linux等系统，出现这个错误可以在网上寻找答案。
*/