int?main(){
int?x,y,r;
char?c;?
do{
printf("輸入壹個點的x?y坐標（x與y之間以空格分隔）:");
scanf("%d?%d",&x,&y);
getchar();
r=x*x+y*y;
if(r==16){
printf("點在圓上。\n");
}else?if(r<=16){
printf("點在圓內。\n");
}else{
printf("點在圓外。\n");
}
printf("是否繼續（y?-?繼續，n?-?不，退出）:");
scanf("%c",&c);
}while(c=='y'?||?c=='Y');
printf("感謝使用！\n");
return?0;
}