实验二 选择结构程序设计

（1）

#include <stdio.h>

int main()
{
	char a,b,c,d,e;
	a = getchar();
	b = getchar();
	c = getchar();
	d = getchar();
	e = getchar();
	putchar(a);
	putchar(b);
	putchar(c);
	putchar(d);
	putchar(e);
	putchar("\n");
	return 0;
}

 

（2）

#include<stdio.h>

int main()
{
	int year,month,days;
	month = 2;
	printf("input the year:");
	scanf("%d",&year);
	if((year % 4 == 0 && year % 100 != 0)|| year % 400 == 0 && year % 100 == 0)
	{
		days=29;
		printf("year:");
		printf("%d\n",year);
		printf("month:");
		printf("%d\n",month);
		printf("days:");
		printf("%d\n",days);
	}
	else{
		days=28;
        printf("year:");
		printf("%d\n",year);
		printf("month:");
		printf("%d\n",month);
		printf("days:");
		printf("%d\n",days);
	}

return 0;
}

 

（3）

#include<stdio.h>
#include<math.h>

int main()
{
	int a,b,c;
	scanf("%d%d%d",&a,&b,&c);
	if((a+b)>c && (a+c)>b && (b+c)>a)
	{
		printf("能构成三角形\n");

	    if((pow(a,2)+pow(b,2)==pow(c,2)) || (pow(a,2)+pow(c,2)==pow(b,2)) || (pow(b,2)+pow(c,2)==pow(a,2)))
		{
			printf("直角三角形\n");
		}
		if((a==b)||(a==c)||(b==c))
		{
			if((a==b)&&(a==c)&&(b==c))
			{
				printf("等边三角形\n");
			}
			else
			{
				printf("等腰三角形\n");
			}
		}
	}
	else
	{
		printf("不能构成三角形\n");
	}

return 0;
}

 

（4）

#include<stdio.h>

int main()
{
	double a,rate,tax,profit;
	printf("input a:");
	scanf("%lf",&a);
	if(a<500)
	{
		rate = 0.00;
		tax = a * rate;
		profit = a - tax;
	}
	else if(a>=500 && a<1000)
	{
	    rate = 0.05;
		tax = a * rate;
		profit = a - tax;
	}
	else if(a>=1000 && a<2000)
	{
	    rate = 0.08;
		tax = a * rate;
		profit = a - tax;
	}
	else if(a>=2000 && a<5000)
	{
	    rate = 0.10;
		tax = a * rate;
		profit = a - tax;
	}
	else if(a>5000)
	{
	    rate = 0.15;
		tax = a * rate;
		profit = a - tax;
	}

	printf("%lf\n%lf\n%lf\n",rate,tax,profit);

return 0;
}

#include<stdio.h>

int main()
{
	int c;
	double a,rate,tax,profit;
	printf("please enter a:");
	scanf("%lf",&a);
	if(a>=5000) c=10;
	else        c=a/500;
	switch(c)
	{
	case 0: rate=0.00;break;
	case 1: rate=0.05;break;
	case 2: 
	case 3: rate=0.08;break;
	case 4:
	case 5:
	case 6:
	case 7:
	case 8:
	case 9: rate=0.10;break;
	case 10: rate=0.15;break;
	}

	tax = a * rate;
	profit = a - tax;
	printf("%lf\n%lf\n%lf\n",rate,tax,profit);

return 0;
}