第一个例子
#include<stdio.h>
main
{
      printf("Hello World!\n");
 }

第二个例子
#include<stdio.h>
main
{
     int x,y,m;
     printf("please input x and y\n");
     scanf("%d%d",&x,&y);
     m=x*y;
     printf("%d * %d = %d\n",x,y,m);
 }

谢谢！！！

发现了，谢谢哈

不错哈

学习了

第三个程序
#include<stdio.h>
main()
{
   float x,y,c;
   printf("Please input x and y :\n");
   scanf("%f%f",&x,&y);
   c=x>y?x:y;
   printf("MAX of (%f,%f) is %f",x,y,c);
 }

需不需要加void

#include<stdio.h>
main()
{
   char ch,nch;
   int count,k;
   printf("Please input a string with a # in the end.\n");
   scanf("%c",&ch);
   while(ch!="#")
    {
       if(ch>='0'&&ch<='9')           
          {
              count=ch-'0'+1;
              scanf("%c",&nch);
              for(k=0;k<count;k++)
                 printf("%c",nch);
           }
        else
           printf("%c",ch);
        printf(" ");
        scanf("%c",&ch);
     }
     pringf("#\n");
}
请问ch>='0'&&ch<='9'和count=ch-'0'+1什么意思，谢谢!

你看上面那个例子后面的问题上面意思