2018-11-14 695 views 1

C++ Primer Plus（第五版）第9章编程题答案

1. 下面是一个头文件：

（……省略……）

根据这个头文件，创建一个多文件程序。其中的一个文件名为golf.cpp，它提供了与头文件中的原型匹配的函数定义；另一个文件应包含main()，并演示原型化函数的所有特性。例如，包含一个让用户输入的循环，并使用输入的数据来填充一个由golf结构组成的数组，数组被填满或用户将高尔夫选手的姓名设置为空字符串时，循环将结束。main()函数只使用头文件中原型化的函数来访问golf结构。

golf.cpp

#include<iostream>
#include <string>
#include <cstring>
#include"golf.h"
using namespace std;
void setgolf(golf & g, const char *name, int hc)
{
	strcpy(g.fullname, name);
	g.handicap = hc;
}
int setgolf(golf & g)
{
	cout << "Please enter the full name of golf player: ";
	cin.getline(g.fullname, Len);
	if (strcmp(g.fullname, "") == 0)
	{
		return 0;
	}

	cout << "Please enter the hanicap of golf player: ";
	cin >> g.handicap;
	cin.get();

	return 1;
}

void handicap(golf & g, int hc)
{
	g.handicap = hc;
}

void showgolf(const golf & g)
{
	cout << "Here is the golf contents:\n";
	cout << "Name: " << g.fullname << endl;
	cout << "Handicap: " << g.handicap << endl;
}

#include<iostream>

#include <string>

#include <cstring>

#include"golf.h"

using namespace std;

void setgolf(golf & g, const char *name, int hc)

{

strcpy(g.fullname, name);

g.handicap = hc;

}

int setgolf(golf & g)

{

cout << "Please enter the full name of golf player: ";

cin.getline(g.fullname, Len);

if (strcmp(g.fullname, "") == 0)

{

return 0;

}

cout << "Please enter the hanicap of golf player: ";

cin >> g.handicap;

cin.get();

return 1;

}

void handicap(golf & g, int hc)

{

g.handicap = hc;

}

void showgolf(const golf & g)

{

cout << "Here is the golf contents:\n";

cout << "Name: " << g.fullname << endl;

cout << "Handicap: " << g.handicap << endl;

}

2. 修改程序清单9.8：用string对象代替字符数组。这样，该程序将不再需要检查输入的字符串是否过长，同时可以将输入字符串同字符串“”进行比较，以判断是否为空行。

#include<iostream>
#include<string>
#include<cstring>
using namespace std;
const int ArSize = 10;
void strcount(const string & str);

int main() {

	string str;
	cout << "Enter a line: \n";
	getline(cin, str);
	while (str != "") {
		strcount(str);
		cout << "Enter next line(empty line to quit): \n";
		getline(cin, str);
	}
	cout << "Bye\n";
	system("pause");
	return 0;
}


void strcount(const string & str){

	using namespace std;
	static int total = 0;
	int count = 0;
	cout << "\"" << str << "\" contains ";
	count = str.length();
	total += count;
	cout << count << " characters\n";
	cout << total << " characters total\n";
}

#include<iostream>

#include<string>

#include<cstring>

using namespace std;

const int ArSize = 10;

void strcount(const string & str);

int main() {

string str;

cout << "Enter a line: \n";

getline(cin, str);

while (str != "") {

strcount(str);

cout << "Enter next line(empty line to quit): \n";

getline(cin, str);

}

cout << "Bye\n";

system("pause");

return 0;

}

void strcount(const string & str){

using namespace std;

static int total = 0;

int count = 0;

cout << "\"" << str << "\" contains ";

count = str.length();

total += count;

cout << count << " characters\n";

cout << total << " characters total\n";

}

3. 下面是一个结构声明：

struct chaff

{

char dross[20];

int slag;

};

编写一个程序，使用定位new运算符将一个包含两个这种结构的数组放在一个缓冲区中。然后，给结构的成员赋值（对于char数组，使用函数strcpy()），并使用一个循环来显示内容。一种方法是像程序清单9.10那样将一个静态数组用作缓冲区；另一种方法是使用常规new运算符来分配缓冲区。

#include<iostream>
#include<new>
#include<cstring>
using namespace std;

struct chaff
{
	char dross[20];
	int slag;
};
void show_struct(chaff & p);
char buffer2[500];
int main()
{
	chaff *p = new(buffer2) chaff[2];
	strcpy(p[0].dross, "Yushuai Zhang");
	strcpy(p[1].dross, "Shandong Province");
	p[0].slag = 23;
	p[1].slag = 100;
	for (int i = 0; i < 2; i++)
	{
		show_struct(p[i]);
	}

	system("pause");
	return 0;
}

void show_struct(chaff & p)
{
	cout << "Dross: " << p.dross << endl;
	cout << "SLAG: " << p.slag << endl;
	cout << endl;
}

#include<iostream>

#include<new>

#include<cstring>

using namespace std;

struct chaff

{

char dross[20];

int slag;

};

void show_struct(chaff & p);

char buffer2[500];

int main()

{

chaff *p = new(buffer2) chaff[2];

strcpy(p[0].dross, "Yushuai Zhang");

strcpy(p[1].dross, "Shandong Province");

p[0].slag = 23;

p[1].slag = 100;

for (int i = 0; i < 2; i++)

{

show_struct(p[i]);

}

system("pause");

return 0;

}

void show_struct(chaff & p)

{

cout << "Dross: " << p.dross << endl;

cout << "SLAG: " << p.slag << endl;

cout << endl;

}

4. 请基于下面这个名称空间编写一个由3个文件组成的程序：

（……省略……）

第一个文件是一个头文件，其中包含名称空间；第二个文件是一个源代码文件，它对这个名称空间进行扩展，以提供这三个函数的定义；第三个文件声明两个Sales对象，并使用setSales()的交互式版本为一个结构提供值，然后使用setSales()的非交互式版本为另一个结构提供值。另外它还使用showSales()来显示这两个结构的内容。

exercise4.h

#pragma once
#ifndef SALES_H_
#define SALES_H_
namespace SALES {
	const int QUARTERS = 4;
	struct Sales
	{
		double sales[QUARTERS];
		double average;
		double max;
		double min;
	};
	void setSales(Sales &s);
	void showSales(const Sales &s);
}
#endif

#pragma once

#ifndef SALES_H_

#define SALES_H_

namespace SALES {

const int QUARTERS = 4;

struct Sales

{

double sales[QUARTERS];

double average;

double max;

double min;

};

void setSales(Sales &s);

void showSales(const Sales &s);

}

#endif

exercise4_fun.cpp

#include<iostream>
#include "exercise4.h"
namespace SALES
{
	void setSales(Sales & s)
	{
		using std::cin;
		using std::cout;
		using std::endl;

		cout << "Enter sales:" << endl;
		for (int i = 0; i < QUARTERS; ++i)
		{
			cout << "sales[" << i << "]: ";
			cin >> s.sales[i];
		}

		// get average, max, min
		double sum = 0.0;
		double max = s.sales[0], min = s.sales[0];
		for (int i = 0; i < QUARTERS; ++i)
		{
			double cur = s.sales[i];
			if (cur > max)
				max = cur;
			if (cur < min)
				min = cur;
			sum += cur;
		}
		s.average = sum / (float)QUARTERS;
		s.max = max;
		s.min = min;
	}

	void showSales(const Sales & s)
	{
		using std::cout;
		using std::endl;

		// show sales
		cout << "SALES: ";
		for (int i = 0; i < QUARTERS; ++i)
			cout << s.sales[i] << " ";
		cout << endl;

		// show average
		cout << "AVERAGE: " << s.average << endl;

		// show max and min
		cout << "MAX: " << s.max << endl;
		cout << "MIN: " << s.min << endl;
	}
}

#include<iostream>

#include "exercise4.h"

namespace SALES

{

void setSales(Sales & s)

{

using std::cin;

using std::cout;

using std::endl;

cout << "Enter sales:" << endl;

for (int i = 0; i < QUARTERS; ++i)

{

cout << "sales[" << i << "]: ";

cin >> s.sales[i];

}

// get average, max, min

double sum = 0.0;

double max = s.sales[0], min = s.sales[0];

for (int i = 0; i < QUARTERS; ++i)

{

double cur = s.sales[i];

if (cur > max)

max = cur;

if (cur < min)

min = cur;

sum += cur;

}

s.average = sum / (float)QUARTERS;

s.max = max;

s.min = min;

}

void showSales(const Sales & s)

{

using std::cout;

using std::endl;

// show sales

cout << "SALES: ";

for (int i = 0; i < QUARTERS; ++i)

cout << s.sales[i] << " ";

cout << endl;

// show average

cout << "AVERAGE: " << s.average << endl;

// show max and min

cout << "MAX: " << s.max << endl;

cout << "MIN: " << s.min << endl;

}

exercise4_main.cpp

#include<iostream>
#include "exercise4.h"

int main(void)
{
	using namespace SALES;
	Sales s1;
	setSales(s1);
	showSales(s1);
	system("pause");
	return 0;
}