Get value between two substrings

I have a string which is CN=van der Valk\, Marco,OU=UT,OU=NL,OU=EMEA,OU=associates,OU=usersAndGroups,DC=corporate,DC=ingrammicro,DC=com.

I only want what is after the CN which will be van der Valk in this case.

I tried it with the trim() function, but didn't succeed. Can anybody help me?

You can use strpos.
First I find the position of CN= and then use that as the offset in the second strpos (to find the end of string).

$str = "CN=van der Valk\, Marco,OU=UT,OU=NL,OU=EMEA,OU=associates,OU=usersAndGroups,DC=corporate,DC=ingrammicro,DC=com";
$CN = strpos($str, "CN=")+3; // +3 because CN= is three characters.
Echo substr($str, $CN, strpos($str, '\\', $CN)-3); // -3 because we need to subtract what we added above.

https://3v4l.org/k5H26

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I'm actually starting to think regex may be a good tool here.
Here I capture both firstname and lastname.
Then remove the slash and explode on comma and save them in $firstname and $lastname.

$str = 'CN=van der Valk\, Marco,OU=UT,OU=NL,OU=EMEA,OU=associates,OU=usersAndGroups,DC=corporate,DC=ingrammicro,DC=com';

preg_match("/CN=([\w\s\\\\,]+),/", $str, $match);

List($lastname, $firstname) = explode(',', str_replace("\\", "", $match[1]));

Echo $firstname ." " . $lastname;

https://3v4l.org/9RN10