public class HelloWorld{
public static void main(String[] args){
int num = 999;
int count = 0;
while(num>0){
num/=10;
count++;
}
System.out.println("它是个"+count+"位的数！");
}
}
public class HelloWorld{
public static void main(String[] args) {
int one = 10 ;
int two = 20 ;
int three = 0 ;
three = one+two;//30
three += one;//40
three -= one;//30
three *= one;//300
three /= one;//30
three %= one;//0
