BigInteger难度大

Question

我试图用Recursion和BigIntegers做Factorial,但eclipse抱怨BigInteger.我知道这个程序本来应该很简单,但它给我带来了麻烦.这是代码.

import java.util.Scanner;
import java.math.BigInteger;

public class Factorial
{
    public static void main(String[] args) 
    {
        Scanner input = new Scanner(System.in);
        System.out.println("Enter integer");
        BigInteger n = input.nextBigInteger();
        System.out.println("Factorial of " + n + " is "  + fact(n));

    }

    public static  int fact(BigInteger n)
    {
        if(n ==0)
        {
            return 1;
        }
        else
        {
            return n * fact(n-1);
        }
    }
}

Answer 1

BigInteger不支持比较使用==和乘法使用*.相反,您必须调用BigInteger类(equals()和multipy())的适当方法.

还要注意存在BigInteger.ZERO和BigInteger.ONE.

最后,您的方法的返回类型fact应该是,BigInteger而不是int.您是希望参数是类型BigInteger还是int由您决定.