Check if UUID is in valid format

verify-uuid.php

<?php
/**
 * Check if a given string is a valid UUID
 * 
 * @param   string  $uuid   The string to check
 * @return  boolean
 */
function isValidUuid( $uuid ) {
    
    if (!is_string($uuid) || (preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', $uuid) !== 1)) {
        return false;
    }

    return true;
}

/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i

@ellisgl method works just fine. Less overhead.

Just another way to write it. Would be interesting to come up with a way to bench mark mupliple regexs...

@ellisgl I actually wanted to mention your method works better lol :)

I ran both 10K times in PHP 7.3.10 //=> 22% faster than the first one.

Wow, I didn't expect that!

@ellisgl's method can give the false positive answer.
If you look at https://tools.ietf.org/html/rfc4122#section-4.1 you can find that not every 128-bits sequence represented in string with hyphens in right places is valid UUID.

@sivolobov should match hex string of 8, 4, 4, 4, 12...

Why not just return (preg_match('/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/', $uuid) === 1);
It's return false isn't a string and the string need to be a UUID.
This means less processing even if it's just a few cycles.

Could leave the '=== 1' off too.

@ellisgl without comparing don't have a Boolean return.
preg_match returns 0, 1, false

Ah, that's right.. ugh.

Thank you ellisgl. Your method works perfectly for me.

@impressto You're welcome.

/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i

@ellisgl works wonderfully - thank you

@cakebake You're welcome.

great gist, I come up with this
return $uuid && preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', $uuid);

/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i

Excelent!! It works fine.

Perfect!

Updated based on @ellisgl suggestion

🤩

One line :)

/**
 * Check if a given string is a valid UUID
 * 
 * @param   mixed  $uuid   The string to check
 * @return  boolean
 */
function isValidUuid(mixed $uuid): bool
{    
    return is_string($uuid) && preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', $uuid);
}