求一个正整数的阶乘 3=3*2*1

import java.util.Scanner;
class Demo6 
{
public static void main(String[] args) 
{
//求一个正整数的阶乘  3=3*2*1
        int num;
long jiecheng = 1;
Scanner sc = new Scanner(System.in);
System.out.println("输入一个正整数");
num = sc.nextInt();


        for(;num>=1;num--)
{
jiecheng = jiecheng*num;
}
System.out.println("jiecheng="+jiecheng);
}
}