[新手求助]错误一个

我刚学C,这段代码是在TC++3.0下编译的,大家帮我看看有什么错误
#include"graphics.h"
void main(void)
{
    int driver,mode;
    driver=DETECT;
    mode=0;
    initgraph(&driver,&mode,"");
    circle(200,200,20);
    circle(200,200,30);
    circle(200,200,40);
    getch();
    restorecrtmode();
}
错误信息是
Error NONAME.C 11:Function 'getch' should have a prototype
谢谢了