murtaza.webdev - 1 month ago 14

Java Question

I was working with one problem and came across this. What happen is:

when we use this:

`BigInteger.valueOf(10000)`

`10000`

But

when we use this

`BigInteger.valueOf(0010000)`

`4096`

Whats the difference between the two?

Answer

00100000 is an octal literal. This has nothing to do with `BigInteger`

- it's just Java integer literals (JLS 3.10.1):

```
System.out.println(10000); // 10000
System.out.println(0010000); // 4096
```

From the JLS:

A decimal numeral is either the single ASCII digit 0, representing the integer zero, or consists of an ASCII digit from 1 to 9 optionally followed by one or more ASCII digits from 0 to 9 interspersed with underscores, representing a positive integer.

...

An octal numeral consists of an ASCII digit 0 followed by one or more of the ASCII digits 0 through 7 interspersed with underscores, and can represent a positive, zero, or negative integer.