Javascript and PHP Regular Expression to exclude different chars

Question

I want to use the PHP function preg_match and the JS function test to exclude strings with this chars: |, +, --, =, <, >, !=, (, ), %, *

Can you give me the correct pattern for this expression ?

Now i use this solution:

    pattern = /[+|=|<|>|(|)|%|*]/;
    if( pattern.test(mystring) )        
    {
        alert(.....);   
    }

But it doesn't work if i use:

pattern = /[+|=|<|>|(|)|%|*|--|!=]/;
if( pattern.test(mystring) )        
{
 alert(....);
}

because it doesn't accept a singular - or !

Anytime you feel stuck with RegEx, head over to http://jsregex.com/ for some practice and for review check out https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/RegExp?redirect=no — Deryck, Nov 30 '13 at 18:03

Pointy · Answer 1 · 2013-11-30T17:52:23.740

1

First, you don't need the | if you're using [ ] - the square brackets imply a match against any one of the characters inside.

To include the - just quote it with \:

var pattern = /[+=<>()%*\-!=|]/;

edit — I was overly hasty in reading your question. To deal with != and --, those will have to be broken out into separate sub-patterns:

var pattern = /[+=<>()%*|]|(!=)|(--)/;

edited Nov 30 '13 at 17:52

answered Nov 30 '13 at 17:34

Pointy

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Just a moment! This pattern exclude a singular - or !. It's not correct for me – Gabriele Mandalari Nov 30 '13 at 17:49
@GabrieleMandalari oh well sorry; I misunderstood. If you need to exclude multi-character patterns it has to be different. I will alter the answer. – Pointy Nov 30 '13 at 17:50

score 1 · Accepted Answer · edited May 23 '17 at 12:05

For JavaScript you want /[+=<>()%*|]|\!=|-{2}/, usage:

new RegExp(/[+=<>()%*|]|!=|-{2}/).test('this!=that');

And in PHP '/[+=<>()%*|]|!=|-{2}/', usage:

preg_match('/[+=<>()%*|]|!=|-{2}/','this!=that');

There is no need to put | (or operator) in your [] (character class) unless you want to match that specific character - this is assumed. Also note that character classes cannot contain a sequence/series of characters; you'll need to break those out and use | to separate the phrases. Here is a breakdown of the regex:

/ - start delimiter
[+=<>()%*|] - match any character in here (singular)
| - matches either what is on the left (character class) or what is on the right (phrase)
!= - match exactly != (phrase)
| - again, matches either what is on the left (phrase) or on the right (phrase)
-{2} - matches the hyphen exactly twice (phrase with a quantifier)
/ - end delimiter

From the high level, it can be interpreted as follows:

A|B|C, either A or B or C match
A is then [D] where any character D matches
D is then +=<>()%*|
B is then !=
C is then E{2} or EE (identical because of the quantifier {n}).
E is then -

Now with your variables and regex instantiation style:

JS:

var pattern = /[+=<>()%*|]|!=|-{2}/;
if( pattern.test(mystring) ) 
{
    console.log(...);
}

PHP:

$pattern = '/[+=<>()%*|]|!=|-{2}/';
if ( preg_match($pattern,$mystring) )
{
    var_dump(...);
}

Bonus: Take a look at What special characters must be escaped in regular expressions? in regards to what characters need to be escaped and in what contexts - in your case, none of them, but still a handy reference!

thank you very much! it works! but you forget that i want to exclude the char "|" now this the solution thanks of your advice: pattern = /[+=<>()%*\|]|!=|-{2}/; — Gabriele Mandalari, Nov 30 '13 at 21:37
@GabrieleMandalari oops! I added `|` to the character class. No need to escape it with a `\ `. Only `^-]\ ` must be escaped inside `[]`. — zamnuts, Nov 30 '13 at 21:43

score 0 · Answer 3 · answered Nov 30 '13 at 17:34

0

You need to escape special chars (for example, parenthesis) using backslash.

answered Nov 30 '13 at 17:34

eRIZ

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score 0 · Answer 4 · answered Nov 30 '13 at 17:35

Your pattern is incorrect in both cases. If you want to use a regular expression to test strings containing those characters just use [+=<>()|&!*-]. This is how you write a character group--you don't put bars between each character. If you want your group to contain -, always place that last (otherwise it might be confused as part of a character range like a-z or 0-9).

Javascript and PHP Regular Expression to exclude different chars

4 Answers4