#include <stdio.h>
int 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>0&&w>0&&h>0)
      if(l==w&&w==h)  
        printf("该箱子是正方体。\n");
      else
        printf("该箱子是长方体。\n");
    else
    printf("输入有误"); 
    return 0;
 } 

#include <stdio.h>
int main()
{    
    int a,b,c,e;
    float sum;//**a打印纸，b墨盒，c光盘,sum最后总金额**// 
    printf("请输入打印纸、墨盒、光盘的数量：\n");
    scanf("%d,%d,%d",&a,&b,&c);
    sum=a*18+b*132+c*4.5;
    if (sum>=5)
        sum=sum*0.9;
    else
    {
        e=sum/100;
        switch(e)
        {
        case1:sum=sum*0.95;
        printf("应付款=%f",sum);
        break;
        case2:sum=sum*0.94;
        printf("应付款=%f",sum);
        break;
        case3:sum=sum*0.93;
        printf("应付款=%f",sum);
        break;
        case4:sum=sum*0.92;
        printf("应付款=%f",sum);
        break;
    }
}
    printf("应付款=%.2f",sum);
}

#include <stdio.h>
int main()
{
    int year,month,days;
    printf("Please enter year and month:\n");
    scanf("%d,%d",&year,&month);
    switch (month)
    {
        case 2 :if(year%400==0||(year%4==0&&year%100!=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("%d年%d月%d天\n",year,month,days);
    return 0;
}

#include <stdio.h>
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（3.5元/支）2、牙膏（6.2元/支）3、肥皂（2元/块）4、毛巾（8.6元/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=2.0*n;break;
            case 4:sum=8.6*n;break;
         } 
         break;
        case 2:printf("请选择：1、笔（3.0元/支）2、笔记本（1.2元/本）3、文件夹（12元/个）4、文具盒（8.6元/个）\n");
        scanf("%d",&y);
        printf("数量");
        scanf("%d",&n);
        switch(y)
        {
            case 1:sum=3.0*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（3.6元/包）2、盐（1.0元/包）3、饼（2元/个）4、方便面（3.6元/条）\n");
        scanf("%d",&y);
        printf("数量");
        scanf("%d",&n);
        switch(y)
        {
            case 1:sum=3.6*n;break;
            case 2:sum=1.0*n;break;
            case 3:sum=2.0*n;break;
            case 4:sum=3.6*n;break;
         } 
         break;
    }
    printf("总计：%.2f元\n",sum);
    return 0; 
}

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

#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>
int main() 
{
    char operator;
    double a,b;
    printf("输入操作符 (+, -, *,/): ");
    scanf("%c", &operator);
    printf("输入两个数字: \n");
    scanf("%lf %lf",&a, &b);
    switch(operator)
    {
        case ‘+‘:
            printf("%.1lf + %.1lf = %.1lf",a, b, a + b);
            break;
 
        case ‘-‘:
            printf("%.1lf - %.1lf = %.1lf",a, b, a - b);
            break;
 
        case ‘*‘:
            printf("%.1lf * %.1lf = %.1lf",a, b, a * b);
            break;
 
        case ‘/‘:
            if(b==0)
              printf("输入错误，分母不能为0\n");
            else
              printf("%.1lf / %.1lf = %.1lf",a, b, a / b);
            break; 
        default:
            printf("输入错误");
    }
}