I'm trying to grab the content between two sets of double underscores, and replace it between two underline html tags, but my regex is not quite right.

str = "**test**";
str = str_replace(/**(\wd )**/g, "<b>$1<\/b>", $str);
// Should echo <b>test</b>

What I'm missing here ?

Thanks.

CodePudding user response：

You need to bear in mind that:

• str_replace does not use regex, you need preg_replace
• /**(\wd )**/g is rather a wrong pattern to use in PHP preg_* functions as the g flag is not supported. More, \wd matches a word char and then one or more d chars, you must have tried to match any alphanumeric chars. (\w ) is enough to use here. * are special regex metacharacters and need escaping.

So you need to use

<?php

$str = "**test**";
$str = preg_replace('/\*\*(\w )\*\*/', '<b>$1</b>', $str);
echo $str;

See the PHP demo.

To match any text between double asterisks, you need

$str = preg_replace('/\*\*(.*?)\*\*/s', '<b>$1</b>', $str);

The s flag will make . also match line break characters.