1 #include<stdio.h>
 2 main()
 3 {
 4     char a,b,c,d;
 5     printf("请输入一个大写字母");
 6     scanf("%c",&a);
 7     b=a+31;
 8     c=a+32;
 9     d=a+33;
10     printf("输出小写字母：%c,%c,%c\n",b,c,d);
11     printf("输出ASCII码:%d,%d,%d\n",b,c,d);
12     
13 }

#include<stdio.h>
int main()
{
 int a,b,c,x,y;
 printf("请输入一个三位的正整数：\n");
 scanf("%d",&x);
 a=x/100;
 b=(x%100)/10;
 c=x%10;
 y=c*100+b*10+a;
 printf("%d: %d\n",x,y);
}

 1     #include<stdio.h>
 2 int main()
 3 {
 4     float x,j,c,hj,fk,zh,cw,g,f;
 5     printf("输入西药费，检查费，材料费，床位费，观察费，护理费：\n");
 6      scanf("%f,%f,%f,%f,%f,%f,",&x,&j,&c,&cw,&g,&f);
 7     hj=x+j+c+cw+g+f;
 8     printf("应付款:%.2f",hj);
 9     printf("病人付款:");
10     scanf("%f",&fk);
11     zh=fk-hj;
12     printf("计算结果:\n");
13     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); 
14 
15 }

 1 #include<stdio.h>
 2 main()
 3 {
 4     float x,y;
 5     printf("请输入x的值:");
 6     scanf("%f",&x);
 7     if(x<1)  y=x;
 8     else
 9     if(x<10) y=2*x-1;
10     else y=3*x-1;
11     printf("y的值为%.2f\n",y);
12     
13 }

 1 #include<stdio.h>
 2 main()
 3 {
 4     int h,f,x,y;
 5     printf("鸡兔总数,鸡兔总脚数:");
 6     scanf("%d,%d",&h,&f);
 7     if(h>0&&f>0)
 8     {
 9         x=(4*h-f)/2;
10         y=(f-2*h)/2;
11         printf("鸡:%d 兔:%d\n",x,y);
12         
13     }
14     else
15     printf("输入错误！\n");
16 }

 1 #include<stdio.h>
 2 #include<math.h>
 3 main()
 4 {   int h=10;
 5     float x1=2,y1=2,x2=-2,y2=2,x3=-2,y3=-2,x4=2,y4=-2,x,y,d1,d2,d3,d4;
 6     printf ("请输入一个点(x,y)");
 7     scanf("%f,%f",&x,&y);
 8     d1=sqrt((x-x1)*(x-x1)+(y-y1)*(y-y1));
 9     d2=sqrt((x-x2)*(x-x2)+(y-y2)*(y-y2));
10     d3=sqrt((x-x3)*(x-x3)+(y-y3)*(y-y3));
11     d4=sqrt((x-x4)*(x-x4)+(y-y4)*(y-y4));
12     if(d1>1&&d2>1&&d3>1&&d4>1)
13     printf("该点高度为：0");
14     else 
15     printf("该点高度为：10");
16 }