C++Primer Plus第6版第9章编程练习

第1题

golf.h头文件

const int len = 40;
struct golf
{
	char fullname[len];
	int handicap;
};
void setgolf(golf&, const char* name, int hc);

int setgolf(golf& g);

void handicap(golf& g, int hc);

void showgolf(const golf& g);

main.cpp

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

const int SIZE = 3;

int main()
{
	using std::cout;
	using std::endl;
	golf andy;
	golf go[SIZE];

	setgolf(andy,"Ann Birdfree",24);
	showgolf(andy);

	for (int i = 0; i < SIZE; i++)
	{
		if (!setgolf(go[i]))
			break;
	}

	handicap(andy, 23);
	showgolf(andy);

	for (int i = 0; i < SIZE; i++)
	{
		if(go[i].fullname[0] != '\0')
			showgolf(go[i]);
	}

	return 0;
}

golf.cpp

#define _CRT_SECURE_NO_WARNINGS//定义宏不然vs认为strcpy函数是不安全的

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

void setgolf(golf& g, const char* name, int hc)
{
	using std::strcpy;

	strcpy(g.fullname, name);
	g.handicap = hc;
}

int setgolf(golf& g)
{
	using std::cout;
	using std::cin;

	cout << "fullname: ";
	cin.getline(g.fullname,len);
	if (g.fullname[0] == '\0')//为空返回0
		return false;
	cout << "handicap: ";
	cin >> g.handicap;
	cin.get();				 //筛选掉换行符

	return true;
}

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

void showgolf(const golf& g)
{
	using std::cout;
	using std::endl;

	cout << g.fullname << ", "
		 <<g.handicap << endl;
}

第二题

修改程序9.9:用string对象替代字符数组。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""进行比较，以判断是否为空行.

#include<iostream>
#include<string>
//常数
const int ArSize = 10;

//功能原型
void strcount(const std::string str);

int main()
{
	using namespace std;
	string input;
	char next;

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

void strcount(const std::string str)
{
	using namespace std;
	static int total = 0;//静态局部变量
	int count = 0;//自动局部变量

	cout << "\"" << str << "\"contains ";
	while (str[count])
		count++;
	total += count;
	cout << count << " characters\n";
	cout << total << " characters total\n";
}

第三题

struct chaff

{

        char dross[20];

        int slag;
}

编写一个程序，使用定位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new运算符来分配缓冲区。

#define _CRT_SECURE_NO_WARNINGS//vs使用strcpy会报错所以添加该宏

#include<iostream>
#include<cstring>
const int SIZE = 100;
static char vo[SIZE];

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

int main()
{
	using namespace std;
	
	charff* opp = new (vo)charff[2];

	strcpy(opp[0].dross, "hello");
	opp[0].slag = 2;
	strcpy(opp[1].dross, "order");
	opp[1].slag = 3;

	for (int i = 0; i < 2; i++)
		cout << opp[i].dross << ", "
			 << opp[i].slag << endl;

	return 0;
}

第四题

头文件sales.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);
}

sales.cpp

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

namespace SALES
{
	void setSales(Sales& s, const double ar[], int n)
	{
		int i, sum, count,temp;

		s.average = sum = count = 0;

		for (i = 0; i < QUARTERS && i < n; i++)
		{
			s.sales[i] = ar[i];
			count++, s.average += s.sales[i];	//有逗号运算符一定要看清
		}

		while (i < QUARTERS)					//设置0
		{
			s.sales[i++] = 0;
		}

		s.average /= count;
		s.min = s.max = s.sales[0];

		for (int k = 1; k < count; k++)
		{
			if (s.max < s.sales[k])
				s.max = s.sales[k];
			else if (s.min > s.sales[k])
				s.min = s.sales[k];
		}
	}

	void setSales(Sales& s)						//交互式
	{
		using std::cin;
		double ar[QUARTERS];					//也可以设置其他的数

		for (int i = 0; i < QUARTERS; i++)
		{
			cin >> ar[i];
		}
		setSales(s, ar, QUARTERS + 1);			//直接调用该函数进行平均值 最大 最小
	}

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

		for (int i = 0; i < QUARTERS; i++)
		{
			cout << "sales " << i + 1
				 << ": " << s.sales[i] << endl;
		}

		cout << "average value: " << s.average
			 << "\nmax: " << s.max << "\nmin : " 
			 << s.min << endl;
	}
}

main.cpp

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

int main()
{
	using namespace SALES;

	Sales s;
	Sales ss;
	double ar[QUARTERS + 1]{ 2.1, 5.1,3.1,4.1,1.1};

	setSales(s, ar, QUARTERS + 1);
	showSales(s);
	std::cout << std::endl;
	setSales(ss);
	showSales(ss);

	return 0;
}