From the NannyMUD documentation

LAST CHANGE

2000-12-14

FUNCTION

NAME
        member_array - Find the position of an element in an array.


SYNTAX
        int member_array(mixed element, mixed *array)

DESCRIPTION
        Gives the index in 'array' which is occupied with the value 'element'.
        If 'element' is not found, -1 is returned.

        Searching works like the equality operator, ie integers and strings
        are compared for equality and arrays and mappings for identity.

        This means that integers and strings must have the same value to match,
        while arrays and mappings must be the exactly same.