unpack

Syntax

unpack(format, buf)

Arguments

format is a format string. See appendix 1.1 Format Characters.

  • A format character may be preceded by an integral repeat count. For example, the format string 4h means exactly the same as hhhh.

  • Whitespace characters between formats are ignored; a count and its format must not contain whitespace though.

  • For the s format character, the count is interpreted as the length of the bytes, not a repeat count like for the other format characters; for example, 10s means a single 10-byte string, while 10c means 10 characters. If a count is not given, it defaults to 1. The string is truncated or padded with null bytes as appropriate to make it fit.

buf is a bytes object. The size of buf in bytes must match the size required by the format.

Details

Unpack from the buffer according to the format string format. The result is a tuple with the unpacked data even if it contains exactly one item.

Examples

$ res = pack("N",1);
$ res1 = unpack("N", res);
$ print(res1)
(1)


$ res = pack("3s i", `123, 3)
$ res1 = unpack("3s i",  res);
$ print(res1)
("123",3)

Appendix

Please see appendix 1.1 Format Characters for the format mapping.

The first character of the format string can be used to indicate the byte order, size and alignment of the packed data, see appendix 1.2 Byte Order, Size, and Alignment. If the first character is not one of these characters, ‘@’ is assumed.

Related functions: pack