@TOC选择结构程序设计

最新推荐文章于 2024-07-12 05:58:34 发布

weixin_44639147

最新推荐文章于 2024-07-12 05:58:34 发布

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本文链接：https://blog.youkuaiyun.com/weixin_44639147/article/details/87799257

@TOC选择结构程序设计

例4.1

#include<stdio.h>
#include<math.h>
int main()
{
double a,b,c,disc,x1,x2,p,q;
scanf("%lf%lf%lf",&a,&b,&c);
disc=b*b-4*a*c;
if(disc<0)
printf("This equation hasn't real roots\n");
else
{p=-b/(2.0*a);
q=sqrt(disc)/(2.0*a);
x1=p+q;
x2=p-q;
printf("real roots:\nxl=%7.2f\nx2=%7.2f\n",x1,x2);
}return 0;
}

在这里插入图片描述例4.2

#include<stdio.h>
int main()
{
float a,b,t;
scanf("%f,%f",&a,&b);
if(a>b)
{
t=a;
a=b;
b=t;
}
printf("%5.2f,%5.2f\n",a,b);
return 0;
}

在这里插入图片描述例4.3

#include<stdio.h>
int main()
{
float a,b,c,t;
scanf("%f,%f,%f",&a,&b,&c);
if(a>b)
{
t=a;
a=b;
b=t;
}
if(a>c)
{
t=a;
a=c;
c=t;
}
if(b>c)
{
t=b;
b=c;
c=t;
}
printf("%5.2f,%5.2f,%5.2f,\n",a,b,c);
return 0;
}

在这里插入图片描述例4.4

#include<stdio.h>
int main()
{
char ch;
scanf("%c",&ch);
ch=(ch>='A'&&ch<='Z')?(ch+32):ch;
printf("%c\n",ch);
return 0;
}
```![在这里插入图片描述](https://img-blog.csdnimg.cn/20190220140027648.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDYzOTE0Nw==,size_16,color_FFFFFF,t_70)

例4.5
```c
#include<stdio.h>
int main()
{
int x,y;
scanf("%d",&x);
if(x<0)
y=-1;
else
if(x==0) y=0;
else
y=1;
printf("x=%d,y=%d\n",x,y);
return 0;
}

在这里插入图片描述例4.6

#include<stdio.h>
int main()
{
char grade;
scanf("%c",&grade);
printf("Your score:");
switch(grade)
{
case'A':printf("85~100\n");break;
case'B':printf("70~84\n");break;
case'C':printf("60~69\n");break;
case'D':printf("<60\n");break;
default:printf("enter data error!\n");
}
return 0;
}
```![在这里插入图片描述](https://img-blog.csdnimg.cn/20190220134100673.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDYzOTE0Nw==,size_16,color_FFFFFF,t_70)例4.7
```c
#include<stdio.h>
int main()
{
void action1(int,int),action2(int,int);
char ch;
int a=15,b=23;
ch=getchar();
switch(ch)
{
case'a':
case'A':action1(a,b);break;
case'b':
case'B':action2(a,b);break;
default:putchar('\a');
}
return 0;
}
void action1(int x,int y)
{printf("x+y=%d\n",x+y);
}
void action2(int x,int y)
{
	printf("x*y=%d\n",x*y);
}

例4.8

#include<stdio.h>
int main()
{
	int year,leap;
	printf("enter year:");
	scanf("%d",&year);
	if(year%4==0)
	{
		if(year%100==0)
		{
			if(year%400==0)
				leap=1;
			else
				leap=0;
		}
		else
			leap=1;
	}
else
leap=0;
if(leap)
printf("%d is ",year);
else
printf("%d is not",year);
printf("a leap year.\n");
return 0;
}

在这里插入图片描述例4.9

#include<stdio.h>
#include<math.h>
int main()
{
	double a,b,c,disc,x1,x2,realpart,imagpart;
	scanf("%lf,%lf,%lf",&a,&b,&c);
	printf("The equation");
	if(fabs(a)<=1e-6)
		printf("is not a quadratic\n");
	else
	{
		disc=b*b-4*a*c;
		if(fabs(disc)<=1e-6)
			printf("has two equl roots:%8.4f\n",-b/(2*a));
		else
			if(disc>1e-6)
			{
				x1=(-b+sqrt(disc))/(2*a);
                x1=(-b-sqrt(disc))/(2*a);
printf("has distinct real roots:%8.4f and %8.4f\n",x1,x2);
			}
			else
			{
				realpart=-b/(2*a);
				imagpart=sqrt(-disc)/(2*a);
				printf("has complex roots:\n");
				printf("%8.4f+%8.4fi\n",realpart,imagpart);
				printf("%8.4f+%8.4fi\n",realpart,imagpart);
			}
	}
	return 0;
}
```![在这里插入图片描述](https://img-blog.csdnimg.cn/20190220150628400.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDYzOTE0Nw==,size_16,color_FFFFFF,t_70)例4.10
```c
#include<stdio.h>

int main()
{
	int c,s;
	float p,w,d,f;
	printf("please enter price,weight,disount:");
	scanf("%f,%f,%d",&p,&w,&s);
	if(s>=3000) c=12;
	else c=s/250;
	switch(c)
	{
	case 0:d=0;break;
	case 1:d=2;break;
    case 2:
	case 3:	d=5;break;
	case 4:
	case 5:
	case 6:
	case 7:d=8;break;
	case 8:
	case 9:
	case 10:
	case 11:d=10;break;
	case 12:d=15;break;
	}
	f=p*w*s*(1-d/100);
	printf("freight=%10.2f\n",f);
	return 0;
}
```![在这里插入图片描述](https://img-blog.csdnimg.cn/20190220151913170.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDYzOTE0Nw==,size_16,color_FFFFFF,t_70)