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The functions in this section test whether the argument is a number or
whether it is a certain sort of number. The functions integerp
and floatp
can take any type of Lisp object as argument (the
predicates would not be of much use otherwise); but the zerop
predicate requires a number as its argument. See also
integer-or-marker-p
, integer-char-or-marker-p
,
number-or-marker-p
and number-char-or-marker-p
, in
Predicates on Markers.
This predicate tests whether its argument is a floating point
number and returns t
if so, nil
otherwise.
floatp
does not exist in Emacs versions 18 and earlier.
This predicate tests whether its argument is an integer, and returns
t
if so, nil
otherwise.
This predicate tests whether its argument is a number (either integer or
floating point), and returns t
if so, nil
otherwise.
The natnump
predicate (whose name comes from the phrase
“natural-number-p”) tests to see whether its argument is a nonnegative
integer, and returns t
if so, nil
otherwise. 0 is
considered non-negative.
This predicate tests whether its argument is zero, and returns t
if so, nil
otherwise. The argument must be a number.
These two forms are equivalent: (zerop x)
≡ (= x 0)
.