析因程序的输出

Question

I am writing a program that should output the factorial of any number which is inputted by the user. The program correctly gives an output from 0 to 12 but if I enter 13, the output is 1932053504 but in my calculator, 13! = 6227020800.

Also in 32! and 33!, the output is negative (32! = -2147483648). Starting 34!, the output is zero(0).

How can I fix this? I want the program to provide the correct output of any number entered by the user.

import java.util.Scanner;
import java.io.*;
    public class one {

        public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number: ");
        int val = in.nextInt();
        int factorial = 1;

        for (int i = 1; i <= val; i++) {
            factorial *= i;
        }
        System.out.println("The factorial of " + val + " is " + factorial);
   }
}

Answer 1

It exceeds the max value an integer can take

Max integer value:2147483647

Max long value: 9223372036854775807

Max double value: 7976931348623157^308

Use long, double or BigInteger, which doesn't have upper boundaries

 public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number: ");
        int val = in.nextInt();
        int factorial = 1;
        int i = 1;
        while (i <= val) {
            factorial = factorial * i;
            i++;
        }
        System.out.println("The factorial of " + val + " is " + factorial);
    }
}

That's how you'd do it with a while loop instead