public class HelloWorld{
public static void main(String[] args){
int num = 999;
int count = 0;
??? if(num>=0&&num<=999999999){
??????? while(num!=0){
??????????? count++;
??????????? num/10
??????? }
??????? System.out.println("它是個(gè)"+ count+"位的數(shù)！");
} else{
System.out.println("輸入有誤！");
??? }
}
}

中的+count+為什么這樣表示啊，旁邊的倆加號(hào)有什么意義