Simple regex problem!

Question

I want to remove everything from a string except numbers, letters, _ (underscore) and : (colon)

It's PREG and I've only come across #\W#, but it removes the : (colon).

Any help is appreciated, thanks!

Answer 1

[^\w:]+ - Remove anything that isn't ([^...]) a letter, digit, underscore (\w) or colon (:).

Sample code:

$ptn = "/[^\w:]+/";
$str = "Hello~~~ World+++: 123";
echo preg_replace($ptn, "", $str);

Outputs: HelloWorld:123