C++ Primer Plus （6th）第六章 编程练习题答案

1.读取键盘输入

#include "stdafx.h"
#include<iostream>
#include<string>

using namespace std;

int main()
{
    char ch=0;
    cout<<"Please enter:";
    while((ch=cin.get())!='@')
    {
        if(isdigit(ch))
        {
            continue;
        } 
        else if (islower(ch))
        {
            cout<<(char)toupper(ch);
        }
        else if (isupper(ch))
        {
            cout << (char)tolower(ch)<<endl;;
        }
    }

    cout << "Ending" << endl;
    return 0;
}

2.存十个数值

#include "stdafx.h"
#include<iostream>
#include<string>
#include<array>

using namespace std;

const unsigned int SIZE=10;

int main()
{
	array<double,SIZE> donation;
	int enter=0;
	double total_value=0.0;
	double avg=0.0;
	int over_avg=0;

	cout<<"Please enter ten doulbe value(Non-numeric to exit):";
	while(enter<10&&(cin>>donation[enter]))
	{
		total_value+=donation[enter];
		enter++;
	}
	avg=total_value/enter;

	for(int i=0;i<enter;i++)
	{
		if(donation[i]>avg)
		{
			over_avg++;
		}
	}

	cout<<"The average value is "<<avg<<",and there are "<<over_avg
		<<" double value more than average !"<<endl;

	return 0;
}

3.菜单驱动程序

#include "stdafx.h"
#include<iostream>
#include<string>

using namespace std;

int main()
{
	char ch=0;
	cout<<"Please enter one of the following choices:\n"
		"c) carnivore     p)pianist \n"
		"t) tree          g)game\n";
	
	while(cin>>ch)
	{
		switch(ch)
		{
		case 'c':
			cout<<"carnivore"<<endl;
			break;
		case 'p':
			cout << "pianist" <<