FAQ: Introduction to PHP Form Validation - Sanitizing for Back-end Storage

This community-built FAQ covers the “Sanitizing for Back-end Storage” exercise from the lesson “Introduction to PHP Form Validation”.

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Hi there,
I’m a bit confused about structure of the pattern in the example as well as in the instructions.
It comes like this: preg_replace("/[^0-9]/", “”, $number);

Why should one use the forward slashes here? They were not necassary before, as far as I remember. And when I dont use them (just “[^0-9]”), then it seems to work just as fine.

Thanks for any help! :slight_smile:
Arne

Welcome to the forums, @java8805287390.

The forward slashes denote the RegularExpression data type. It helps to parse it out of the string object. Regexs are not strings. We also need the slashes if we wish to afix any flags such as g or i.

As for it working without the slashes, test this on a hard refresh before drawing any conclusions. Let us know what happens, either way.

PCRE

Oh, I see. Thanks for the fast answer!
And of course, without the forward slashes it didnt work

1 Like

And you are wiser for knowing how to test before drawing any conclusions. One thing we learn when going down the PHP road is that mistakes are never forgiven. One minor slip-up and the response document is a white page with response code 500. Test, test and test again. Unlike JavaScript, PHP is not our friend.