Version: 1.6.0

# Sequences of bytes

Bytes are used for serializing data, for example to compute signature hashes. Conversely, they can be used to deserialise external data, in which case the expected LIGO type needs to be specified.

### Literals​

Byte literals are sequences of bytes (eight-bit values, also known as octets), defined using the prefix `0x` followed by hexadecimal digits, or none if the denoted literal is zero:

const a : bytes = 0x70FF;
const zero : bytes = 0x;
const zero_too = 0x00;

Clearly, this means that literal bytes are always comprised of an even number of hexadecimal digits (because one hexadecimal digit requires up to four bits in binary, and eight are needed to make up a byte).

### From numbers to bytes and back​

Some other numerals can be converted to bytes by means of calling the predefined function `bytes`, which is overloaded. The reverse conversion is done by the predefined functions `int` and `nat`. For instance, here how to create bytes from natural numbers and integers:

const b: bytes = bytes(123n); // 7B in hexadecimal
const c: bytes = bytes(123);
const d: bytes = bytes(-123); // Two's complement
const n: nat = nat(0x7B); // n == 123n
const i: int = int(0x7B); // i == 123

Note: See Two's complement.

### From strings​

A string literal can be converted to bytes in two ways:

1. by interpreting the ASCII code of each character (which spans over two hexadecimal digits) as one byte;
2. by interpreting directly each character as one hexadecimal digit.

In the former case, the syntax is somewhat odd -- as opposed to simply calling the function `bytes`:

const from_ascii: bytes = bytes`foo`; // Not a call

The latter case is implemented as a type cast:

// raw == from_ascii
const raw: bytes = ("666f6f" as bytes);

Note that both syntaxes apply respectively only to verbatim string literals and general strings, not general expressions of type `string`. In other words, the contents of the strings must be available at compile-time. (This actually reveals that ```("666f6f" as bytes)``` is not really a cast, as casts are non-operations.)