#include<stdio.h>
main()
{
    int l,w,h;
    printf("请输入箱子的长,宽,高;\n");
    scanf("%d%d%d",&l,&w,&h);
    if(l==w&&l==h&&w==h)
    printf("该箱子是正方体\n");
    else
    printf("该箱子是长方体\n");
    
 } 

#include<stdio.h>
main()
{
    int a,b,c,x;
    float sum;
    printf("打印纸 18 yuan/本  墨盒 132yuan/个   光盘 4.5yuan/张\n");
    scanf("%d%d%d",&a,&b,&c);
    sum=18*a+132*b+4.5*c;
    x=sum/100;
    switch(x)
    {
      case 0:printf("sum=%.2f\n",sum); break;
      
      case 1:printf("sum=%.2f\n",sum*0.95); break; 
      
      case 2:printf("sum=%.2f\n",sum*0.94); break; 
       
      case 3:printf("sum=%.2f\n",sum*0.93); break;
            
      case 4:printf("sum=%.2f\n",sum*0.92); break;
            
      case 5:printf("sum=%.2f\n",sum*0.90); break;
    }
 } 

#include<stdio.h>
main()
{
    int year,month,days;
    printf("please enter year and month:\n");
    scanf("%d%d",&year,&month);
    switch(month)
{
        case 2:if((year%4==0&&(year%100==!0))||year%400==0)
            days=29;
            else
            days=28;
            break;
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:days=31;
            break;
            case 4:
            case 6:
            case 9:
            case 11:days=30;
            break;
    }
    printf("天数为:%d",days);
}

#include<stdio.h>
int main()
{
    int x,n,y;
    float sum=0.0;
    printf("请选择：1，日用品 2，文具 3，食品\n");
    scanf("%d",&x);
    switch(x)
    {
        case 1:printf("请选择:1.牙刷(3.5YUAN/支) 2.牙膏(6.2yuan/支)\n");
               printf("       3.肥皂(2yuan/块)   4.毛巾(8.6yuan/条)\n");
               scanf("%d",&y);
               printf("数量？");
               scanf("%d",&n);
               switch(y)
               {
                   case 1:sum=3.5*n;break;
                   case 2:sum=6.2*n;break;
                   case 3:sum=2*n;break;
                   case 4:sum=8.6*n;break;
                } 
                break;
        case 2:printf("请选择:1.笔(3YUAN/支) 2.笔记本(1.2yuan/支)\n");
               printf("       3.文件夹(12yuan/块)   4.文具盒(8.6yuan/条)\n");
               scanf("%d",&y);
               printf("数量？");
               scanf("%d",&n);
               switch(y)
               {
                   case 1:sum=3*n;break;
                   case 2:sum=1.2*n;break;
                   case 3:sum=12*n;break;
                   case 4:sum=8.6*n;break;
               }
               break;
        case 3:printf("请选择:1.白糖(3.6YUAN/支) 2.盐(1yuan/支)\n");
               printf("       3.饼(2yuan/块)   4.方便面(3.6yuan/条)\n");
               scanf("%d",&y);
               printf("数量？");
               scanf("%d",&n);
               switch(y)
               {
                   case 1:sum=3.6*n;break;
                   case 2:sum=1*n;break;
                   case 3:sum=2*n;break;
                   case 4:sum=3.6*n;break;
               }
               break;
              
     } 
    printf("总计:%.2f yuan\n",sum);
    return 0;
 } 

#include<stdio.h>
int main()
{
    double x=1000/3.0;
    double y=x-333.0;
    double z=3*y-1.0;
    printf("x=%lf\n",x);
    printf("y=%lf\n",y);
    printf("z=%lf\n",z);
    if(z==0) printf("z==0.\n");
         else printf("z不等于0.\n");
    return 0;
}

#include<stdio.h>
int main()
{
    int num=20;
    if(5<num&&num<10)
        printf("%d in range (5,10)!\n",num);
    else
    printf("%d out of range (5,10)!\n",num); 
}

#include<stdio.h>

main()
{
    int x,y,z,a,b,c,d,m;
 do{
 
    printf("选择计算类型：\n 1--------加法\n 2--------减法\n 3--------乘法\n 4--------除法\n");    
    scanf("%d",&z);
    printf("z=%d\n",z);     
    printf("请输入计算的两个数："); 
    scanf("%d%d",&x,&y);    
    a=x+y;
    b=x-y;
    c=x*y;
    d=x/y;    
    switch(z)    
    {
     case 1:printf("%d+%d=%d",x,y,a);
                break;
     case 2:printf("%d-%d=%d",x,y,b);        
                break;  
     case 3:printf("%d*%d=%d",x,y,c);        
                break;  
     case 4: printf("%d/%d=%d",x,y,d);        
                break;  
    default:printf("输出错误！");
    }
    printf("继续输入请按 1 \n");
    scanf("%d",&m); 
  }  while(m==1);
}