int with leading 0's behave strangely

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Integer with leading zeroes

Can someone please tell me what is going on here? When I initialize an int with leading zeroes the program does not ignore the zeroes and instead does some other operation I am unaware of.

int num = 0200;

System.out.println(num); // 128

System.out.println(033); // 27

@aaaa bbbb: Did you click the `close` link and *actually* vote to close? Are you just just saying you think you should vote to close? — S.Lott, Sep 02 '11 at 20:38
I'm not a registered user, so I don't get to actually close. — aaaa bbbb, Sep 02 '11 at 20:39

score 11 · Accepted Answer · answered Sep 02 '11 at 20:35

11

Sure - it's treating it as an octal literal, as per the Java Language Specification, section 3.10.1:

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

OctalDigits:
        OctalDigit
        OctalDigit OctalDigits

OctalDigit: one of
        0 1 2 3 4 5 6 7
Note that octal numerals always consist of two or more digits; 0 is always considered to be a decimal numeral-not that it matters much in practice, for the numerals 0, 00, and 0x0 all represent exactly the same integer value.

answered Sep 02 '11 at 20:35

Jon Skeet

1,421,763
867
9,128
9,194

Of course I don't know why I couldn't think of that. It gave an error when I put a 9 in there! Thanks for the fast reply, Jon! – Andrew Sep 02 '11 at 20:36
Ok, im deleting my answer. The Java specification should be clear enough. – Tom Sep 02 '11 at 20:39

score 6 · Answer 2 · answered Sep 02 '11 at 20:35

6

That's an octal (base 8) literal.

Similarly, 0x27 is a hexadecimal (base 16) literal, with a decimal value of 39.

answered Sep 02 '11 at 20:35

SLaks

868,454
176
1,908
1,964

int with leading 0's behave strangely

2 Answers2