[RESOLVED] Replace except after a certain character

[navster]

Please could anyone enlighten me on how I would archive the following!!

I want to replace a space with an underscore except when the space is after a comma. So something like this

tag 1, tag 2, tag 3

becomes

tag_1, tag_2, tag_3

[laserlight]

You could consider regex, e.g.,

$text = 'tag 1, tag 2, tag 3';
echo preg_replace('/(?<!,) /', '_', $text);

[navster]

Thanks very much laserlight! 😃

[xblue]

Or, without lookbehind

$text = 'tag 1, tag 2, tag 3'; 
echo preg_replace('/([^,]) /', '$1_', $text);

(Unlike Laserlight's pattern, this would not replace a space at the beginning of the string, not sure if that is crucial to you.)