#include <stdio.h>
#include <stdlib.h>
#include <graphics.h>
#include <conio.h>

int main(void)
{
   
    char directKey;
    int x=450, y =300, radius =50;
   
  
    initwindow(900 , 600);  
    setcolor(YELLOW);  
   
       outtextxy(10, 10, "=============圓形移動程式=============");
    outtextxy(10, 30, "按數字鍵8開始移動");
        
    circle(x, y, radius);         
   
    while(directKey!=17)                    
    {
                     
          directKey=getch();   
          clearviewport();     

           witch(directKey)
    {
              case 56:        
              y-=5;
              break;
                                          
     }
      circle(x, y, radius);   
    }
    return 0;
}



如题，这个是手动按8让圆往上移动，那怎么能让他自动往上呢？