(PHP 3>= 3.0.3, PHP 4 )

strspn --  Find length of initial segment matching mask


int strspn ( string str1, string str2)

Returns the length of the initial segment of str1 which consists entirely of characters in str2.

The line of code:

$var = strspn("42 is the answer, what is the question ...", "1234567890");

will assign 2 to $var, because the string "42" will be the longest segment containing characters from "1234567890".

See also strcspn().