Reg ex and not match

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sks - 09 Jul 2006 10:12 GMT

I'm a bit stuck on how to not match something in a reg ex,

Ie, if I wanted to test that a string did not begin with ABC

Do I have to use a character class and do something like this
[^(ABC)]

???

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hiwa - 09 Jul 2006 10:33 GMT

sks :

> I'm a bit stuck on how to not match something in a reg ex,
>
[quoted text clipped - 4 lines]
>
> ???

Basically and generally, regular expression can't do it.
But your Java program that utilizes regex could do.

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Jeffrey Schwab - 09 Jul 2006 16:41 GMT

> I'm a bit stuck on how to not match something in a reg ex,
>
> Ie, if I wanted to test that a string did not begin with ABC
>
> Do I have to use a character class and do something like this
> [^(ABC)]

No. The character-class will match one character that is none of A, B,
C, or either parenthesis. Try this:

Pattern.compile("^(?!ABC)");

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Oliver Wong - 10 Jul 2006 15:48 GMT

> I'm a bit stuck on how to not match something in a reg ex,
>
[quoted text clipped - 4 lines]
>
> ???

Your regular expression would basically say this (in plain English):

( String does NOT start with A. )
OR
( String starts with A, but does NOT have a B following it)
OR
( String starts with AB, but does not have a C following it)

I'm not familiar with Java's specific syntax for regular expressions,
but it'd probably look something like:

([^A])|(A[^B])|(AB[^C])

possibly with the addition of "string start" and "string end" markers.

- Oliver

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Reg ex and not match

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