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Editorial Team
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Asked: 2026-05-15T12:29:11+00:00

I want to replace word groups by links. The word groups are defined in

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I want to replace word groups by links.

The word groups are defined in a multi-dimensional array. There will be thousands of terms to be replaced, so an unindexed, light-weight and multi-dimensional array is needed.

Nothing should be replaced when the term is followed by brackets or inside square brackets.

Problem:
The regex itself works fine, but the replacement breaks when the word groups include regex syntax characters like + ? / ( etc.
So I need to mask them. I tried all variations I can think of but it won’t work for all cases. I can’t mask them in $text or $s.

<?php

$text = "<html><body><pre>
Replace all foo / bar / baz cases here:
Case 1: Text Foo text.
Case 2: Text 'Foo' Bar text Foo.
Case 3: Text Foobar (2) text.
Case 4: Text Bar & Baz.
Case 5: Text Bar Baz?
Case 6: Text Bar? & Baz?
Case 7: Text Bar-X.

Replace nothing here (text followed by brackets) or [inside square brackets]: 
Case 1: Text Foo (text).
Case 2: Text 'Foo' Bar (text) Foo (text).
Case 3: Text Foobar (2) (text).
Case 4: Text Bar & Baz (text).
Case 5: Text Bar Baz (text).
Case 6: Text Bar? & Baz (text).
Case 7: Text Bar-X (text).
Case 8: [Text Foo]
</pre></body></html>";

$s = array(
  array("t" => "Foo",         "u" => "http://www.foo.net"),
  array("t" => "'Foo' Bar",   "u" => "http://www.foo.net"),
  array("t" => "Foobar (2)",  "u" => "http://www.foo.net"),
  array("t" => "Bar & Baz",   "u" => "http://www.foo.net"),
  array("t" => "Bar Baz?",    "u" => "http://www.foo.net"),
  array("t" => "Bar? & Baz?", "u" => "http://www.foo.net"),
  array("t" => "Bar-X",       "u" => "http://www.foo.net")
 );

$replaced = $text;
foreach ($s as $i => $row) {
# $replaced = preg_replace('/(?='.preg_quote($row["t"]).'[^\]][^(]+$)\b'.preg_quote($row["t"]).'\b/mS',
# $replaced = preg_replace('/(?='.preg_quote($row["t"], '/').'[^\]][^(]+$)\b'.preg_quote($row["t"], '/').'\b/mS',
# $replaced = preg_replace('/(?=\Q'.$row["t"].'\E[^\]][^(]+$)\b\Q'.$row["t"].'\E\b/mS',
    $replaced = preg_replace('/(?='.$row["t"].'[^\]][^(])\b'.$row["t"].'\b/mS',
                           '<a href="'.$row["u"].'">'.$row["t"].'</a>',
                           $replaced);
 }
echo $replaced;

?>
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1 Answer

  1. Editorial Team

    This should work, at least at provided test cases:

    $replaced = preg_replace('/([.,\s!^]+)('.preg_quote($row["t"],'/').')([.,\s!$]+)(?!\()/mS',
                           '$1<a href="'.$row["u"].'">$2</a>$3',
                           $replaced);

    \b doesn’t work as expected when your match itself is wrapped inside some boundaries (like in Foobar (2)), so you should specifically provide a list of allowed characters. I quickly put [.,\s!^] and [.,\s!$] there, you probably will have to add some more allowed characters according to your specs (like -, _?)

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