clojure.core/byte-array

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Type: function Added: Clojure 1.1 Examples: 3 Runnable: 0

([size-or-seq] [size init-val-or-seq])

Creates an array of bytes

Examples

by shockbob on 2011-08-21 . May have evaluation errors. ▶

;; create an array of bytes ;; and demonstrate that you can use it in the standard Java fill function ;; note the needed byte coercion in the fill function call (def bees (byte-array 10)) #'user/bees (for [i (range 10)](aset-byte bees i (* i i))) (0 1 4 9 16 25 36 49 64 81) (vec bees) [0 1 4 9 16 25 36 49 64 81] (java.util.Arrays/fill bees (byte 122)) nil (vec bees) [122 122 122 122 122 122 122 122 122 122]

by guruma on 2016-02-19 . May have evaluation errors. ▶

;; copied from the example in clojure.core/byte (def x (byte-array [(byte 0x43) (byte 0x6c) (byte 0x6f) (byte 0x6a) (byte 0x75) (byte 0x72) (byte 0x65) (byte 0x21)])) #'user/x (String. x) "Clojure!"

by nivekuil on 2020-11-30 . May have evaluation errors. ▶

;; NOTE: equality uses identity, not value semantics. (= (byte-array 10) (byte-array 10)) false (java.util.Arrays/equals (byte-array 10) (byte-array 10)) true (def a (byte-array [(byte 0x43)])) #'user/a (def b (byte-array [(byte 0x43)])) #'user/b (= a b) false (java.util.Arrays/equals a b) true

Note by dspearson

The maximum size of a byte-array is Integer/MAX_VALUE, as arrays are int-indexed in Java. However, it is possible to pass a value that is larger than this, resulting in a cast that will wrap around. This incorrect usage will not give any indication of error.

Note by luposlip

To type hint a byte array, use this non-obvious syntax:

(.write ^OutputStream output-stream ^"[B" bytearray)

Note by brunchboy

You can also use ^bytes to type hint a byte array, and as of Clojure 1.12, ^byte/1 for a one-dimensional byte array, ^byte/2 for two dimensions, etc.

See also

• clojure.core/bytes (0)
• clojure.core/byte (0)

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