(PHP 3 >= 3.0.3, PHP 4, PHP 5)
strspn -- 
     Find length of initial segment matching mask
    
Description
int 
strspn ( string str1, string str2 [, int start [, int length]] )
     Returns the length of the initial segment of
     str1 which consists entirely of characters
     in str2.
    
     The line of code:
     
     will assign 2 to 
$var, because the string "42" will
     be the longest segment containing characters from "1234567890".
    
     As of PHP 4.3.0, strspn() accepts two optional 
     integer parameters that can be used to define the 
     start position and the 
     length of the string to examine.
    
     
    Note: This function is
binary-safe.
     See also strcspn().