Binaries in elixir are created using the Kernel.SpecialForms construct <<>>.
They are a powerful tool which makes Elixir very useful for working with binary protocols and encodings.
Binaries and bitstrings are specified using a comma delimited list of integers or variable values, bookended by "<<" and ">>". They are composed of 'units', either a grouping of bits or a grouping of bytes. The default grouping is a single byte (8 bits), specified using an integer:
<<222,173,190, 239>> # 0xDEADBEEF
Elixir strings also convert directly to binaries:
iex> <<0, "foo">> <<0, 102, 111, 111>>
You can add "specifiers" to each "segment" of a binary, allowing you to encode:
These specifiers are encoded by following each value or variable with the "::" operator:
<<102::integer-native>> <<102::native-integer>> # Same as above <<102::unsigned-big-integer>> <<102::unsigned-big-integer-size(8)>> <<102::unsigned-big-integer-8>> # Same as above <<102::8-integer-big-unsigned>> <<-102::signed-little-float-64>> # -102 as a little-endian Float64 <<-102::native-little-float-64>> # -102 as a Float64 for the current machine
The available data types you can use are:
Be aware that when specifying the 'size' of the binary segment, it varies according to the 'type' chosen in the segment specifier: