► |  | The Racket Reference

1 | Language Model
2 | Syntactic Forms
3 | Datatypes
4 | Structures
5 | Classes and Objects
6 | Units
7 | Contracts
8 | Pattern Matching
9 | Control Flow
10 | Concurrency and Parallelism
11 | Macros
12 | Input and Output
13 | Reflection and Security
14 | Operating System
15 | Memory Management
16 | Unsafe Operations
17 | Running Racket
| Bibliography
| Index

► | 3 | Datatypes

3.1 | Booleans and Equality
3.2 | Numbers
3.3 | Strings
3.4 | Byte Strings
3.5 | Characters
3.6 | Symbols
3.7 | Regular Expressions
3.8 | Keywords
3.9 | Pairs and Lists
3.10 | Mutable Pairs and Lists
3.11 | Vectors
3.12 | Boxes
3.13 | Hash Tables
3.14 | Sequences and Streams
3.15 | Dictionaries
3.16 | Sets
3.17 | Procedures
3.18 | Void and Undefined

▼ | 3.2 | Numbers

3.2.1 | Number Types
3.2.2 | Generic Numerics
3.2.3 | Flonums
3.2.4 | Fixnums

On this page:

number?
complex?
real?
rational?
integer?
exact-integer?
exact-nonnegative-integer?
exact-positive-integer?
inexact-real?
fixnum?
flonum?
double-flonum?
single-flonum?
zero?
positive?
negative?
even?
odd?
exact?
inexact?
inexact->exact
exact->inexact
real->single-flonum
real->double-flonum

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##### 3.2.1`` Number Types

> > procedure

> > (number? v) → boolean?

> v : any/c

Returns #t if v is a number, #f otherwise.

Examples:

> > (number? 1)
> #t
> > (number? 2+3i)
> #t
> > (number? "hello")
> #f

> > procedure

> > (complex? v) → boolean?

> v : any/c

Returns (number? v), because all numbers are complex numbers.

> > procedure

> > (real? v) → boolean?

> v : any/c

Returns #t if v is a real number, #f otherwise.

Examples:

> > (real? 1)
> #t
> > (real? +inf.0)
> #t
> > (real? 2+3i)
> #f
> > (real? 2.0+0.0i)
> #f
> > (real? "hello")
> #f

> > procedure

> > (rational? v) → boolean?

> v : any/c

Returns #t if v is a rational number, #f otherwise.

Examples:

> > (rational? 1)
> #t
> > (rational? +inf.0)
> #f
> > (rational? "hello")
> #f

> > procedure

> > (integer? v) → boolean?

> v : any/c

Returns #t if v is a number that is an integer, #f otherwise.

Examples:

> > (integer? 1)
> #t
> > (integer? 2.3)
> #f
> > (integer? 4.0)
> #t
> > (integer? +inf.0)
> #f
> > (integer? 2+3i)
> #f
> > (integer? "hello")
> #f

> > procedure

> > (exact-integer? v) → boolean?

> v : any/c

Returns (and (integer? v) (exact? v)).

Examples:

> > (exact-integer? 1)
> #t
> > (exact-integer? 4.0)
> #f

> > procedure

> > (exact-nonnegative-integer? v) → boolean?

> v : any/c

Returns (and (exact-integer? v) (not (negative? v))).

Examples:

> > (exact-nonnegative-integer? 0)
> #t
> > (exact-nonnegative-integer? -1)
> #f

> > procedure

> > (exact-positive-integer? v) → boolean?

> v : any/c

Returns (and (exact-integer? v) (positive? v)).

Examples:

> > (exact-positive-integer? 1)
> #t
> > (exact-positive-integer? 0)
> #f

> > procedure

> > (inexact-real? v) → boolean?

> v : any/c

Returns (and (real? v) (inexact? v)).

> > procedure

> > (fixnum? v) → boolean?

> v : any/c

Return #t if v is a fixnum, #f otherwise.

Note: the result of this function is platform-dependent, so using it in syntax transformers can lead to platform-dependent bytecode files.

> > procedure

> > (flonum? v) → boolean?

> v : any/c

Return #t if v is a flonum, #f otherwise.

> > procedure

> > (double-flonum? v) → boolean?

> v : any/c

Identical to flonum?.

> > procedure

> > (single-flonum? v) → boolean?

> v : any/c

Return #t if v is a single-precision floating-point number, #f otherwise.

> > procedure

> > (zero? z) → boolean?

> z : number?

Returns (= 0 z).

Examples:

> > (zero? 0)
> #t
> > (zero? -0.0)
> #t

> > procedure

> > (positive? x) → boolean?

> x : real?

Returns (> x 0).

Examples:

> > (positive? 10)
> #t
> > (positive? -10)
> #f
> > (positive? 0.0)
> #f

> > procedure

> > (negative? x) → boolean?

> x : real?

Returns (< x 0).

Examples:

> > (negative? 10)
> #f
> > (negative? -10)
> #t
> > (negative? -0.0)
> #f

> > procedure

> > (even? n) → boolean?

> n : integer?

Returns (zero? (modulo n 2)).

Examples:

> > (even? 10.0)
> #t
> > (even? 11)
> #f
> > (even? +inf.0)
> even?: contract violation
> expected: integer
> given: +inf.0

> > procedure

> > (odd? n) → boolean?

> n : integer?

Returns (not (even? n)).

Examples:

> > (odd? 10.0)
> #f
> > (odd? 11)
> #t
> > (odd? +inf.0)
> odd?: contract violation
> expected: integer
> given: +inf.0

> > procedure

> > (exact? z) → boolean?

> z : number?

Returns #t if z is an exact number, #f otherwise.

Examples:

> > (exact? 1)
> #t
> > (exact? 1.0)
> #f

> > procedure

> > (inexact? z) → boolean?

> z : number?

Returns #t if z is an inexact number, #f otherwise.

Examples:

> > (inexact? 1)
> #f
> > (inexact? 1.0)
> #t

> > procedure

> > (inexact->exact z) → exact?

> z : number?

Coerces z to an exact number. If z is already exact, it is returned. If z is +inf.0, -inf.0, or +nan.0, then the exn:fail:contract exception is raised.

Examples:

> > (inexact->exact 1)
> 1
> > (inexact->exact 1.0)
> 1

> > procedure

> > (exact->inexact z) → inexact?

> z : number?

Coerces z to an inexact number. If z is already inexact, it is returned.

Examples:

> > (exact->inexact 1)
> 1.0
> > (exact->inexact 1.0)
> 1.0

> > procedure

> > (real->single-flonum x) → single-flonum?

> x : real?

Coerces x to a single-precision floating-point number. If x is already a single-precision floating-point number, it is returned.

> > procedure

> > (real->double-flonum x) → flonum?

> x : real?

Coerces x to a double-precision floating-point number. If x is already a double-precision floating-point number, it is returned.
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