You can test an object to see whether it is a marker, or whether it is either an integer or a marker. The latter test is useful in connection with the arithmetic functions that work with both markers and integers.
markerp
object ¶This function returns t
if object is a marker, nil
otherwise. Note that integers are not markers, even though many
functions will accept either a marker or an integer.
integer-or-marker-p
object ¶This function returns t
if object is an integer or a marker,
nil
otherwise.
number-or-marker-p
object ¶This function returns t
if object is a number (either
integer or floating point) or a marker, nil
otherwise.