undefinedp

NAME

undefinedp() - determine whether or not a given variable is undefined.

SYNOPSIS

int undefinedp( mixed arg );

DESCRIPTION

Return 1 if 'arg' is undefined.  'arg' will be undefined in the follow‐
ing cases:

1.  it is a variable set equal to the return value of a call_other to a
    non-existent method (e.g. arg = call_other(obj, "???")).

2.  it  is  a variable set equal to the return value of an access of an
    element  in  a   mapping   that   doesn't   exist   (e.g.   arg   =
    map[not_there]).

SEE ALSO

mapp(3),  stringp(3),  pointerp(3),  objectp(3),  intp(3),  bufferp(3),
floatp(3), functionp(3), nullp(3), errorp(3)