My code is not producing the correct output

Question

 long fact= 1;
 for(int i=1;i<=n;i++){
     fact=fact*i;
 }
 System.out.println(fact);

The code should produce factorial of large numbers, for example 25. But the output is not correct.

Would it be possible for you to edit the headline to something that describes your problem better? As it stands, it's rather generic. — Henrik Aasted Sørensen, Aug 14 '20 at 10:42
Does it output anything at all? or it's stuck? give us specific example, and we can help you better. — Giorgi Tsiklauri, Aug 14 '20 at 10:43
25! will be in the order of 10^27 = 10^(3*9) = 2^(10*9) = 90 bits. So it exceeds a long. Use `BigInteger`. — Joop Eggen, Aug 14 '20 at 10:49

score 3 · Answer 1 · answered Aug 14 '20 at 10:48

3

Like Samir Vyas said "It exceeds the number range which can be represented by java long type."
If you want to bypass this limit, you will need to use a BigInteger or a BigDecimal.
You can find more information on this question Large Numbers in Java

answered Aug 14 '20 at 10:48

Vincent VDV

31
1
6

score 2 · Answer 2 · edited Aug 14 '20 at 15:32

2

It exceeds the number range which can be represented by java long type.

https://docs.oracle.com/javase/8/docs/api/java/lang/Long.html

edited Aug 14 '20 at 15:32

Pshemo

122,468
25
185
269

answered Aug 14 '20 at 10:46

Samir Vyas

442
2
6

WJS · Answer 3 · 2020-08-31T20:01:09.297

Try this.

int n = 30;                                
System.out.printf("%d! = %,d%n",n,fact(n));

public static BigInteger fact(int fact) {        
    BigInteger f = BigInteger.valueOf(fact);     
    while (--fact > 1) {                         
        f = f.multiply(BigInteger.valueOf(fact));
    }                                            
    return f;                                    
}

Prints

30! = 265,252,859,812,191,058,636,308,480,000,000

For more information on arbitrary precision math check out BigInteger and BigDecimal in the JDK API.

My code is not producing the correct output

3 Answers3