Supported letter codes:

• 'z': zero-terminated string
• 'p': string preceded by length byte
• 'P': string preceded by length word
• 'a': string preceded by length size_t
• 'A': string
• 'f': float
• 'd': double
• 'n': Lua number
• 'c': char
• 'b': byte = unsigned char
• 'h': short
• 'H': unsigned short
• 'i': int
• 'I': unsigned int
• 'l': long
• 'L': unsigned long
• 'x': unsigned char
• '<': little endian
• '>': big endian
• '=': native endian
• '{': unbreakable little endian
• '}': unbreakable big endian

This library was made by Luiz Henrique de Figueiredo (lhf@tecgraf.puc-rio.br) with contributions from Ignacio Castaño (castanyo@yahoo.es) and Roberto Ierusalimschy (roberto@inf.puc-rio.br). Original library can be found here.

Usage examples

Type pack

Type pack

Field(s)

pack.pack(F, x1)

Parameters

• F : a string describing how the values x1, x2, ... are to be interpreted and formatted. Each letter in the format string F consumes one of the given values.
• x1 : x2, ... : variable number of values. Only values of type number or string are accepted.

Return value

a (binary) string containing the values packed as described in F.

Usage:

require"pack"
local bindata = string.pack("zf", "foo", 4.2)

pack.unpack(s, F, init)

Parameters

• s : is a (binary) string containing data packed as if by pack
• F : is a format string describing what is to be read from s
• init : optional init marks where in s to begin reading the values

Return values

1. the next unread position in s, followed by one value per letter in F until F or s is exhausted.
2. nil if either s has been exhausted or init is bigger than the length of the s

Usage:

  require"pack"
  local _,mystring,myfloat = string.unpack(bindata, "zf")