Skip to main content

realp

realp Function

Syntax:

realp object → generalized-boolean

Arguments and Values:

object—an object.

generalized-boolean—a generalized boolean.

Description:

Returns true if object is of type real; otherwise, returns false.

Examples:

(realp 12) → true 

(realp #c(5/3 7.2)) → false 
(realp nil) → false 
(realp (cons 1 2)) → false

Notes:

(realp object) ≡ (typep object ’real)

Expanded Reference: realp​

Testing if an object is a real number​

realp returns true if the object is a real number, which includes integers, ratios, and floats.

(realp 12)
=> T
(realp 3/4)
=> T
(realp 3.14)
=> T
(realp -7.5d0)
=> T

Complex numbers are not real​

Complex numbers, even those with zero imaginary parts written explicitly, are not of type real.

(realp #c(5/3 7.2))
=> NIL
(realp #c(1 0))
=> T

Non-numeric objects​

realp returns false for all non-numeric types.

(realp nil)
=> NIL
(realp "42")
=> NIL
(realp (cons 1 2))
=> NIL
(realp 'foo)
=> NIL

Relationship to other type predicates​

All integers, rationals, and floats are real. Real numbers are a subset of numbers that excludes complex numbers.

(and (realp 42) (integerp 42))
=> T
(and (realp 1/3) (rationalp 1/3))
=> T
(and (realp 3.0) (floatp 3.0))
=> T
(and (numberp #c(1 2)) (not (realp #c(1 2))))
=> T

Equivalence to typep​

realp is equivalent to (typep object 'real).

(eql (realp 42) (typep 42 'real))
=> T
(eql (realp #c(1 2)) (typep #c(1 2) 'real))
=> T