C++PrimerPlus（第六版）第九章答案

第1题：

golf.cpp

#pragma warning (disable :4996)
#include <iostream>
#include "golf.h"
#include <string>

using namespace std;

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

int setgolf(golf& g)
{
	char name[Len];
	int hc;
	cout << "请输入姓名:";
	cin.get(name, Len);
	cin.ignore(Len, '\n');
	cout << "请输入hc：";
	cin >> hc;
	cin.get();
	if (strcmp(name, " ") == 0)
	{
		return 0;
	}
	else
	{
		strcpy(g.fullname, name);
		g.handicap = hc;
		return 1;
	}
}

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

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

golf.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);

main.c

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

int main()
{
	using namespace std;
	golf in[5];

	for (int i = 0; i < 5; i++)
	{
		char name[Len];
		int hc;
		int result = 1;
		if (i % 2 == 0)
		{
			cout << "此为模式2：\n";
			result = setgolf(in[i]);
		}
		else
		{
			cout << "此为模式1：\n请输入姓名：";
			cin.get(name, Len);
			cin.ignore(Len, '\n');
			cout << "请输入hc:";
			cin >> hc;
			cin.get();
			setgolf(in[i], name, hc);
			if (strcmp(name, " ") == 0)
			{
				result = 0;
			}
		}
		if (result == 0)
		{
			break;
		}
		if (i == 3)
		{
			handicap(in[i], 7);
		}
		showgolf(in[i]);
	}
	return 0;
}

第2题：

#pragma warning (disable:4996)
#include <iostream>
#include <string>
const int ArSize = 10;
void strcount(const std::string str);

int main()
{
	using namespace std;
	string input;
	char next;
	cout << "Enter a line:\n";
	getline(cin,input);
	while (cin)
	{
		strcount(input);
		cout << "Enter next line(empty line to quit):\n";
		getline(cin,input);
		if (input==" ")
		{
			break;
		}
	}
	cout <<"Bye\n" ;
	return 0;
}

void strcount(const std::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";
}
//原代码处理了超过数组长度的字符
//此代码未做该处理
//类似的处理见第1题中的 golf.cpp 的第20行 cin.ignore(Len, '\n');

第3题：

#pragma warning (disable:4996)
#include <iostream>
#include <string>
#include <new>

using namespace std;

struct chaff
{
	char dross[20];
	int slag;
};

char b[50];

int main()
{
	int i=0;
	cout <<(void*) b<<endl;
	chaff *a1 = new (b) chaff[2];
	chaff *a2 = new chaff[2];
	for (i=0;i<3;i++)
	{
		int n;
		char name[20];
		cout << "输入字符串：";
		cin >> name;
		cout << "输入数字:";
		cin >> n;
		strcpy(a1[i].dross, name);
		a1[i].slag = n;
		cout << "输入字符串：";
		cin >> name;
		cout << "输入数字.";
		cin >> n;
		strcpy(a2[i].dross, name);
		a2[i].slag = n;

	}
	cout << a1<<"\t";
	cout << a2<<endl;
	for(i=0;i<3;i++)
	{ 
		cout << a1[i].dross<<"\t"<<a1[i].slag<<"\t"<<&a1[i]<<endl<<endl;
		cout << a2[i].dross << "\t" << a2[i].slag<<"\t"<<&a2[i]<<endl<<endl;
	}
		return 0;
}

第4题：

headfile_4.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 );
	void setSales(Sales & s);
	void showSales(const Sales &s);
}

c_4.cpp

#include "headfile_4.h"
#include <iostream>
#include<iomanip>

namespace SALES
{
	void setSales(Sales& s, const double ar[], int n)
	{
		double min, max, aver;
		min = ar[0];
		max = ar[0];
		aver = 0.0;
		int i;
		for (i = 0; i < n; i++)
		{
			s.sales[i] = ar[i];
			if (min > ar[i])
			{
				min = ar[i];
			}
			if (max < ar[i])
			{
				max = ar[i];
			}
			aver += ar[i];
		}
		while (i < QUARTERS)
		{
			s.sales[i] = 0.0;
			i++;
		}
		aver /= n;
		s.min = min;
		s.max = max;
		s.average = aver;
	}
	void setSales(Sales& s)
	{
		std::cout << "请输入s的值：";
		double min;
		double max;
		double aver;
		double n;
		for (int i = 0; i < 4; i++)
		{
			std::cin >> n;
			if (i == 0)
			{
				min = n;
				max = n;
				aver = 0.0;
			}
			else
			{
				if (min > n)
				{
					min = n;
				}
				if (max < n)
				{
					max = n;
				}
			}
			s.sales[i] = n;
			aver += n;
		}
		aver /= 4;
		s.average = aver;
		s.max = max;
		s.min = min;
	}
	void showSales(const Sales& s)
	{
		using namespace std;
		cout << "s.sales:" << endl;
		for (int i = 0; i < 4; i++)
			cout << s.sales[i] << "\t";
		cout << endl;
		cout << left << setw(20) << "s.average:" << s.average << endl;
		cout << left << setw(20) << "s.max:" << setw(20) << s.max << endl;
		cout << left << setw(20) << "s.min:" << setw(20) << s.min << endl;
	}
}

main.cpp

#pragma warning (disable:4996)
#include <iostream>
#include <string>
#include <new>
#include"headfile_4.h"
using namespace std;
using namespace SALES;

int main()
{
	Sales s1,s2;
	double ar1[2] = {462.3,580.66};
	setSales(s1,ar1,2);
	setSales(s2);
	cout << "s1:"<<endl;
	showSales(s1);
	cout << "s2:" << endl;
	showSales(s2);
	return 0;
}