preg_match(): Unknown modifier

Question

Currently using the following string as my pattern. (Warning: preg_match(): Unknown modifier '0')

$between = preg_match("(.*)".$check."(.*)", _allbetween($coords1, $coords2));

What am I doing wrong?

Have never used regular expressions in php before, please excuse this probably extremely simple question.

Casimir et Hippolyte · Accepted Answer · 2014-01-22T23:33:46.050

2

You must add delimiters to your pattern and use preg_quote if $check contains a literal string:

preg_match("/(.*)".preg_quote($check)."(.*)/", _allbetween($coords1, $coords2));

Note that preg_match returns 1 or 0 (true or false), not the match result (see the php manual)

edited Jan 22 '14 at 23:33

answered Jan 22 '14 at 23:25

Casimir et Hippolyte

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This works perfectly. I'll be selecting your answer for simplicity! – Stormageddon S. Anderson Jan 22 '14 at 23:29

feeela · Answer 2 · 2014-01-22T23:32:47.747

A regular expression in PHP must be enclosed by a pair of characters, that do not occur in the regexp itself (and if, they mus be escaped using a backslash).

Which character you use is defined through the first char – a ( in your case. But a bracket already has a special meaning in regexp.

You should enclose your regexp by the most common delimiter / (a slash), as in:

$between = preg_match( sprintf( '/(.*)%s(.*)/', preg_quote( $check ) ), _allbetween($coords1, $coords2));

see: http://php.net/manual/en/regexp.reference.delimiters.php
and maybe also: http://php.net/manual/en/function.preg-quote.php as you should always escape user inputs to regular expression (if $check is one…)

preg_match(): Unknown modifier

2 Answers2