NOTE: You may think this function returns true or false, but it returns a 0-based index or -1, so please be sure to use it appropriately.
•Checks to see if $value is in the array of values named $arrayname
•Returns the first index into the array that equals $value or returns -1 if $value is not found in the array
•1 - case-sensitive search (else performs a case-insensitive search)
•NOTE: This function is deprecated; use array_search() instead.