为什么在Java BigInteger中divide（）函数不起作用？

Question

I'm attempting to divide the variable 'c' by 2(stored in 'd'). For some reason that doesn't happen. I'm passing 10 and 2 for input right now.

import java.util.*;
import java.lang.*;
import java.io.*;
import java.math.BigInteger;

class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
    Scanner sc = new Scanner(System.in); 
    BigInteger a = new BigInteger(sc.next()); 
    BigInteger b = sc.nextBigInteger();
    BigInteger d = new BigInteger("2"); 
    System.out.println(d);

    BigInteger c = a.subtract(b); 
    c.divide(d);
    System.out.println(c);
    a.subtract(c); 

    System.out.println(a); 
    System.out.println(c);
    }
} 

Any help would be appreciated. Thanks in advance!

Answer 1

You are forgetting that BigInteger is immutable. That means that a.divide(b) does not change a it returns the result of the calculation .

You need a = a.divide(b) or similar.

    BigInteger a = new BigInteger(sc.next());
    BigInteger b = sc.nextBigInteger();
    BigInteger d = new BigInteger("2");
    System.out.println(d);

    BigInteger c = a.subtract(b);
    // HERE!
    c = c.divide(d);
    System.out.println(c);
    // HERE!
    a = a.subtract(c);

    System.out.println(a);
    System.out.println(c);

Answer 2

BigInteger is immutable. You get the result of c.divide(d); as the return value, which you throw away in your code.