《C++ Primer Plus（第六版）》（15）（第九章 内存模型和命名空间 编程题答案）

1.

Test.h

#ifndef _Test_H_
#define _Test_H_

const int Len = 40;
struct golf
{
	char fullname[Len];
	int handicap;
};

void setgolf(golf& g, const char* name, int hc);
int setgolf(golf& g);
void handicap(golf& g, int hc);
void showgolf(const golf& g);
#endif

Test.cpp

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

using namespace std;
void setgolf(golf& g, const char* name, int hc)
{
	strcpy_s(g.fullname, name);
	g.handicap = hc;
}

int setgolf(golf& g)
{
	cout << "Please enter fullname: ";
	cin.get();
	cin.getline(g.fullname, 40);
	if (strcmp(g.fullname, "") == 0)
	{
		return 0;
	}
	cout << "Please enter handcap: ";
	cin >> g.handicap;
	return 1;
}

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

void showgolf(const golf& g)
{
	cout << g.fullname << ": " << g.handicap << endl;
}

main.cpp

#include <iostream>   
#include "Test.h"
using namespace std;

 
int main(int argc, const char * argv[]) 
{
	golf g[5];

	char str[40] = "";
	int hc = 0;
	cout << "Please enter fullname: ";
	cin >> str;
	cout << "Please enter handcap: ";
	cin >> hc;
	setgolf(g[0], str, hc);
	int num = 1;
	for (int i = 1; i < 5; i ++)
	{
		if (setgolf(g[i]) == 0)
		{
			break;
		}
		num++;
	}
	cout << "Show Golf" << endl;
	for (int i = 0; i < num; i++)
	{
		showgolf(g[i]);
	}
	return 0;
}
 

2.

修改前：

#include <iostream>   
#include "Test.h"
using namespace std;

const int ArSize = 10;
void strcount(const char* str);

int main(int argc, const char * argv[]) 
{
	char input[ArSize];
	char next;
	cout << "Enter a line:\n";
	cin.get(input, ArSize);
	while (cin)
	{
		cin.get(next);
		while (next != '\n')
		{
			cin.get(next);//取出多余的字符扔掉
		}
		strcount(input);
		cout << "Enter next line(empty line to quit):\n";
		cin.get(input, ArSize);
	}
	cout << "Bye\n";
	return 0;
}

void strcount(const char* str)
{
	static int total = 0;
	int count = 0;
	cout << "\"" << str << "\" contains ";
	while (*str++)
	{
		count++;
	}
	total += count;
	cout << count << " character\n";
	cout << total << " characters total\n";
}
 

修改后：

#include <iostream>   
#include "Test.h"
#include <string>
using namespace std;

void strcount(const string& str);

int main(int argc, const char * argv[]) 
{
	string input;
	cout << "Enter a line:\n";
	getline(cin, input);
	while (cin)
	{ 
		strcount(input);
		cout << "Enter next line(empty line to quit):\n";
		getline(cin, input);
	}
	cout << "Bye\n";
	return 0;
}

void strcount(const string& str)
{
	static int total = 0;
	int count = str.length();
	cout << "\"" << str << "\" contains ";
	total += count;
	cout << count << " character\n";
	cout << total << " characters total\n";
}
 

3.

#include <iostream>   
#include "Test.h"
#include <new>
using namespace std;
const int BUF = 512;
const int N = 2;
char buffer[BUF];
struct chaff 
{
	char dross[20];
	int slag;
};


int main(int argc, const char * argv[]) 
{
	//使用静态数组作为缓冲区
	chaff* cf = new(buffer)chaff[N];
	for (int i = 0; i < N; i ++)
	{
		cout << "Please enter dross: ";
		char dross[20];
		cin.getline(dross,20);
		strcpy_s(cf[i].dross, dross);
		cout << "Please enter slag:";
		cin >> cf[i].slag;
		cin.get();
	}
	 
	for (int i = 0; i < N; i++)
	{
		cout << cf[i].dross << " : " << cf[i].slag << endl;
	}
	
	//使用动态数组作为缓冲区
	char* buffer2 = new char[BUF];


	chaff* cf2 = new(buffer2)chaff[N];
	for (int i = 0; i < N; i++)
	{
		cout << "Please enter dross: ";
		char dross[20];
		cin.getline(dross, 20);
		strcpy_s(cf2[i].dross, dross);
		cout << "Please enter slag:";
		cin >> cf2[i].slag;
		cin.get();
	}


	for (int i = 0; i < N; i++)
	{
		cout << cf2[i].dross << " : " << cf2[i].slag << endl;
	}


	cf2 = NULL;//把这个置为空指针
	delete[] buffer2;//把缓冲区删除了
	return 0;
}

4.

Test.h

#ifndef _Test_H_
#define _Test_H_

namespace SALES
{
	const int QUARTERS = 4;
	struct Sales
	{
		double sales[QUARTERS];
		double average;
		double max;
		double min;
	};
	void setSales(Sales & s, const double ar[], int n);
	void setSales(Sales & s);
	void showSales(const Sales& s);
}
 
#endif

Test.cpp

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

using namespace std;
void SALES::setSales(Sales & s, const double ar[], int n)
{ 
	double total = 0;
	for (int i = 0; i < QUARTERS; i++)
	{
		if (i >= n)
		{
			s.sales[i] = 0;
		}
		else
		{
			s.sales[i] = ar[i];
		}
		if (i == 0)
		{
			s.max = s.sales[i];
			s.min = s.sales[i];
		}
		else
		{
			if (s.sales[i] > s.max)
			{
				s.max = s.sales[i];
			}
			if (s.sales[i] < s.min)
			{
				s.min = s.sales[i];
			}
		}
		total += s.sales[i];
	}
	s.average = total / QUARTERS;
}

void SALES::setSales(Sales & s)
{
	double d[QUARTERS];
	for (int i = 0; i < QUARTERS; i++)
	{
		cout << "Enter the sales:";
		cin >> d[i];
	}
	setSales(s, d, QUARTERS);
}

void SALES::showSales(const Sales& s)
{
	cout << "Sales:";
	for (int i = 0; i < QUARTERS; i++)
	{
		cout << s.sales[i];
		cout << ", ";
	}
	cout << "\nMin:" << s.min << " Max:" << s.max << " average:" << s.average << endl;
}

main.cpp

#include <iostream>   
#include "Test.h"
#include <new>
using namespace std;
 

int main(int argc, const char * argv[]) 
{
	double d[4] = { 123.3, 323, 342.333, 8933 };
	SALES::Sales s1, s2;
	setSales(s1, d, 4);
	setSales(s2);
	showSales(s1);
	showSales(s2);
	return 0;
}