Regex Question - Exclude Certain Characters

Question

If I want to exclude /* in regex how would I write it?

I have tried:

[^/[*]]
([^/][^*])

But to no avail...

Can you give more details? What sort of input are you expecting? What should be captured/matched, and what shouldn't? — bdukes, May 09 '11 at 14:06
@ Matt Ball - Sorry, I'm using Java. It's in relation to this post which is driving me nuts - http://stackoverflow.com/questions/5937504/regex-question-newbie — user559142, May 09 '11 at 14:18
In future regex questions, **please** specify the programming language/regex flavor. — Matt Ball, May 09 '11 at 14:31
BTW, I've found [this page](http://www.regexplanet.com/simple/) to be a useful tool for Java regex. — Matt Ball, May 09 '11 at 14:32

orlp · Accepted Answer · 2011-05-09T15:04:35.557

3

You must match not /, OR / followed by not *:

([^/]|/[^*])+/?

edited May 09 '11 at 15:04

answered May 09 '11 at 14:07

orlp

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Why must the regex match no `/`s? – Matt Ball May 09 '11 at 14:08
1

No, it's a trick. You match anything but `/` or a `/` followed by anything but `*`. – orlp May 09 '11 at 14:09
Is it not possible to do it in one? i.e. just ignore /* in that order?? – user559142 May 09 '11 at 14:17
1

But this will not match a `/` at the end of the string. – Bart Kiers May 09 '11 at 14:49

Matt Ball · Answer 2 · 2011-05-09T14:24:49.393

2

Use a negative lookahead to check that, if the input contains /, it does not contain / followed by /*. In JavaScript, x not followed by y would be x(?!y), so:

Either the input contains no /: new RegExp('^[^/]*$'), or
Any / found must not be followed by *: new RegExp('^/(?!\\*)$') (note, the * must be escaped with a \\ since * is a special character.

To combine the two expressions:

new RegExp('^([^/]|/(?!\\*))*$')

edited May 09 '11 at 14:24

answered May 09 '11 at 14:06

Matt Ball

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I was trying this, it doesn't work... all it does it capture standalone `/` characters, it doesn't get anything else. From the question it sounds like he wants everything except those. – eykanal May 09 '11 at 14:07

score 0 · Answer 3 · answered May 09 '11 at 14:28

In Java following Pattern should work for you:

Pattern pt = Pattern.compile("((?<!/)[*])");

Which means match * which is NOT preceded by /.

TEST CODE

String str = "Hello /* World";
Pattern pt = Pattern.compile("((?<!/)[*])");
Matcher m = pt.matcher(str);
if (m.find()) {
    System.out.println("Matched1: " + m.group(0));
}
String str1 = "Hello * World";
m = pt.matcher(str1);
if (m.find()) {
    System.out.println("Matched2: " + m.group(0));
}

OUTPUT

Matched2: *

score 0 · Answer 4 · answered May 10 '11 at 00:44

Can't you just deny a positive match? So the kernel is just "/*", but the * needs masking by backslash, which needs masking itself, and the pattern might be followed or preceded by something, so .* before and after the /\\* is needed: ".*/\\*.*".

val samples = List ("*no", "/*yes", "yes/*yes", "yes/*", "no/", "yes/*yes/*yes", "n/o*")  
samples: List[java.lang.String] = List(*no, /*yes, yes/*yes, yes/*, no/, yes/*yes/*yes, n/o*)

scala> samples.foreach (s => println (s + "\t" + (! s.matches (".*/\\*.*"))))                   
*no true
/*yes   false
yes/*yes    false
yes/*   false
no/ true
yes/*yes/*yes   false
n/o*    true

score -1 · Answer 5 · answered May 28 '16 at 05:00

-1

See http://mindprod.com/jgloss/regex.html#EXCLUSION

e.g. [^"] or [^w-z] for anything but quote and anything but wxyz

answered May 28 '16 at 05:00

user1332994

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The OP already knows about negated character classes, and they don't solve the problem. – Alan Moore May 28 '16 at 06:37

Regex Question - Exclude Certain Characters

5 Answers5

TEST CODE

OUTPUT

Linked