c primer plus 习题答案(1)

这是我做的c primer plus（第五版）上的部分习题解答，一些类似的就不发了。我用的IDE是visual studio 2013。

p186.3

#include<stdio.h>
#include<stdlib.h>
#define SIZE 30
int main(void)
{
    int o_num=0, e_num=0; 
    int i, j; 
    int num[SIZE];
    printf("please input number
");
    scanf("%d", &num[i]);
    j=0;

    for(i=0;num[i++]!=0;)
    {
        if(num[i]%2==0)
        {
            j++;
            e_num+=num[i];
        }
        else
            o_num+=num[i];
    }
    printf("%d %d", j, e_num/j);
    printf("%d %d", i-j, o_num/(i+1-j));

    system("pause");
    return 0;
}

p187.6

A方案

#include<stdio.h>
#include<stdlib.h>

int main(void)
{
    int num=0;
    char ch;

    while(1)
    {
        if((ch=getchar())=='#')
            break;
        if(ch=='e'&&(ch=getchar())=='i')
            num++;
        else if(ch=='#')
            break;
    }

    printf("%d", num);

    system("pause");
    return 0;
}

 B方案

#include<stdio.h>
#include<stdlib.h>

int main(void)
{
    int num=0;
    char ch;

    while(1)
    {
        if((ch=getchar())=='#')
            break;
        else if(ch=='e')
        {
            switch(ch=getchar())
        {
                case 'i': num++;
                case '#': break;}
        if(ch=='#')
            break;}
        if(ch=='#')
        break;
    }

    printf("%d", num);

    system("pause");
    return 0;
}

p187.8

#include<stdio.h>
#include<stdlib.h>
int get_int(void);
#define BASETIME 40
#define RATE1 0.15
#define RATE2 0.2
#define RATE3 0.25


int main(void)
{
    float time, gross, net_income, tax, payrate, i;

    for(i=1;i<=48;i++)
        printf("*");
    printf("
");
    printf("Enter the number correspongding to the desired pay rate or action:
");
    printf("1)$%-.2f/hr%18c 2)$%-.2f/hr%18c
", 8.75, ' ',9.33,' ');
    printf("3)$%-.2f/hr%18c4)$%-.2f/hr%18c
", 10.00, ' ',11.20,' ');
    printf("5)quit");
    printf("
");
    for(i=1;i<=48;i++)
        printf("*");
    printf("
");

    while(1)
    {
    printf("Please enter your pay rate.
");
    switch(get_int())
    {        
        case 1: payrate=8.75;
                break;
        case 2: payrate=9.33;
                break;
        case 3: payrate=10.00;
                break;
        case 4: payrate=11.20;
                break;
        case 5: break;             
    }
    if(get_int()==5)
        break;
    printf("Please enter your working hours.
");
    while(scanf("%f", &time)==1)
    {
        if(time<=40)
            if(time<=30)
                printf("the gross/tax/net_income is %f %f %f",time*payrate, time*payrate*RATE1, time*payrate-time*payrate*RATE1);
            else
                printf("the gross/tax/net_income is %f %f %f",300+(time-30)*payrate, 300*RATE1+(time-30)*payrate*RATE2, (300+(time-30)*payrate)-(300*RATE1+(time-30)*payrate*RATE2));
        else if(time>40)
            printf("the gross/tax/net_income is %f %f %f",450+(time-40)*1.5*payrate, 300*RATE1+150*RATE2+(time-40)*1.5*payrate*RATE3, 450+(time-40)*1.5*payrate-300*RATE1-150*RATE2-(time-40)*1.5*payrate*RATE3);
        printf("
");
        printf("enter q to quit.
");
    }
    }    

    system("pause");
    return 0;
}


int get_int(void)
{
    int num;

        scanf("%d", &num);
        switch(num)
        {
        case 1: return num;
                break;
        case 2: return num;
                break;
        case 3: return num;
                break;
        case 4: return num;
                break;
        case 5: return num;
                break;
        default:
            printf("Please input an integer range from 1~5
");
        }
}

 p187.10

#include<stdio.h>
#include<stdlib.h>
int get_char();

int main(void)
{
    int bill;
    double tax;

    while(1)
    {
        printf("Please input your taxable income.
");
        printf("enter q to quit.
");
        if(scanf("%d",&bill)!='1')
            break;
        switch(get_char())
        {
        case '1': if(bill<=17850)
                      tax=0.15*bill;
                  else
                      tax=17850*0.15+(bill-17850)*0.28;
            printf("The tax is %f
", tax);
            break;
        case '2': if(bill<=23900)
                      tax=0.15*bill;
                  else
                      tax=23900*0.15+(bill-23900)*0.28;
            printf("The tax is %f
", tax);
            break;
        case '3': if(bill<=29750)
                      tax=0.15*bill;
                  else
                      tax=29750*0.15+(bill-29750)*0.28;
            printf("The tax is %f
",tax);
            break;
        case '4': if(bill<=14875)
                      tax=bill*0.15;
                  else
                      tax=14875*0.15+(bill-14875)*0.28;
            printf("The tax is %f
",tax);
            break;
        }
    }
    system("pause");
    return 0;
}

int get_char()
{
    int num;
    printf("Please enter a number.
");
    
    while(scanf("%d", &num))
    if(num!=1&&num!=2&&num!=3&&num!=4)
        printf("Please enter again.
");
    else    
        return num;
    
}