C PRIMER PLUS第六版 第六章编程练习

15.

#include <stdio.h>
#include <string.h>

int main()
{
    char string[255];
    int i = -1;
    int s;
    
    printf("Please enter a string:");
    
    do 
    {
        i++;
        scanf("%c",&string[i]);   //用%c一个个将字母录入string
    } while(string[i] != '\n');  //读取到回车时跳出循环
    
    s = strlen(string) - 1;
    
    for(i = s;i >= 0;i--)
    {
        printf("%c",string[i]);
    }
    
    return 0;
}

16.

#include <stdio.h>

int main()
{
    double m,n;
    int i = 0; //用来计数，算出多少年 
    m = n = 100;
    
    do
    {
        m += 100*0.1;
        n *= 1.05;
        i++;
    }while(n < m);
    
    printf("It needs %d years for Deirdre earning more money than Daphne.\n",i);
    printf("Deirdre:%lf\n",n);
    printf("Daphne:%lf\n",m);
    
    return 0;
}

17.

#include <stdio.h>

int main()
{
	double inbank,left;
	int year;  //用来记录年份
	year = 0;
	inbank = 100;
	
	do
	{
		inbank *= 1.08;
		left = inbank - 10;
		inbank = left;
		year++;
	} while(left >= 0);
	
	printf("After %d years, Chuckie Lucky takes all money out.\n",year);
	
	return 0;
}

18.

#include <stdio.h>

int main()
{
	int friends;
	int weeks;
	weeks = 1;
	friends = 5;
	
	do
	{
		friends = 2  * (friends - weeks);
		printf("%d week, Doctor Rabund has %d friends\n",weeks,friends);
		weeks++;
	} while(friends <= 150);
	
	printf("Over Dunbar's number.\n");
	
	return 0;
}