#include <stdio.h>  
main()
{
     char a,b,c;
     printf("请输入一个大写字母:\n");
        scanf("%c",&a);
     b=a+31;
     c=a+33;
     a=a+32;
     printf("小写字母为:%c,%c,%c:\n",b,a,c); 
     printf("ASCII码的值为:%d,%d,%d",b,a,c);
}   

  #include <stdio.h>
    int main()
    {
     int a,b,c,x,y;
     printf("请输入一个3位数：\n");
     scanf("%d",&x);
     a=x/100;
     b=(x-a*100)/10;
     c=x%10;
     y=c*100+b*10+a;
     printf("%d:%d\n",x,y);
     return 0;
    } 

 #include<stdio.h>
    int main()
    {
     float x,j,c,hj,fk,zh,cw,g,f;
     printf("输入医药费，检查费，材料费，床位费，观察费，护理费:\n");
     scanf("f%,%f,%f,%f,%f,%f",&x,&j,&c,&cw,&g,&f);
     hj=x+j+c+cw+g+f;
     printf("应付款（元）:%.2f",hj);
     printf("病人付款（元）:");
     scanf("%f",&fk);
     zh=fk-hj;
     printf("计算结果:\n");
     printf("病人付款=%6.2f元\n应收款=%6.2f元应找回=%6.2f元\n",fk,hj,zh);
     return 0;
    }  

#include<stdio.h>
main()
{
 float x,y;
 printf("请输入x的值：");
        scanf("%f",&x);
 if(x<1) 
    y=x;
 else  if(x<10)
    y=2*x-1;
 else
 y=3*x-1;
 printf("Y的值为%.2f\n",y);
} 

    #include<stdio.h>
    main()
    {
     int h,f,x,y;
     printf("鸡兔总数，鸡兔总脚数:\n");
     scanf("%d,%d",&h,&f);
     if(h>0&&f                                                                                            >0)
     {                                                                                                                 
      x=(4*h-f)/2;
      y=(f-2*h)/2;
      printf("鸡:%d 兔：%d\n",x,y);
     }
     else
     printf("输入错误！\n");
    }  

    #include<math.h>
    main()
    {
     int h=10;
     float x1=2,y1=2,x2=-2,y2=2,x3=-2,y3=-2,x4=2,y4=-2,x,y,d1,d2,d3,d4;
     printf("请输入一个点（x,y）:");
     scanf("%f,%f",&x,&y);
     d1=sqrt((x-x1)*(x-x1)+(y-y1)*(y-y1));
     d2=sqrt((x-x2)*(x-x2)+(y-y2)*(y-y2));
     d3=sqrt((x-x3)*(x-x3)+(y-y3)*(y-y3));
     d4=sqrt((x-x4)*(x-x4)+(y-y4)*(y-y4));
     if(d1>1&&d2>1&&d3>1&&d4>1)
            h=0;
     printf("该点高度为%d",h);
    }