`struct`

Interpret bytes as packed binary data. Convert between Python values and C structs represented as Python bytes objects.

Source-of-record: Modules/_struct.c, Lib/struct.py, struct docs.

Functions

Function	Effect
`pack(format, v1, v2, ...)`	Pack values into bytes.
`unpack(format, buffer)`	Unpack to tuple; buffer must equal `calcsize`.
`pack_into(format, buffer, offset, ...)`	Pack into a writable buffer at offset.
`unpack_from(format, buffer, offset=0)`	Unpack from buffer at offset.
`iter_unpack(format, buffer)`	Iterator of tuples.
`calcsize(format)`	Size in bytes.
`Struct(format)`	Pre-compile a format; reuse `pack`/`unpack` etc.

Char	Byte order	Size	Alignment
`@`	native	native	native (default)
`=`	native	standard	none
`<`	little	standard	none
`>`	big	standard	none
`!`	network (big)	standard	none

Char	C type	Python type	Standard size
`x`	pad byte	-	1
`c`	char	`bytes` of length 1	1
`b` / `B`	signed/unsigned char	`int`	1
`?`	`_Bool`	`bool`	1
`h` / `H`	short/ushort	`int`	2
`i` / `I`	int/uint	`int`	4
`l` / `L`	long/ulong	`int`	4
`q` / `Q`	long long	`int`	8
`n` / `N`	ssize_t/size_t (native only)	`int`	-
`e`	half float	`float`	2
`f` / `d`	float/double	`float`	4 / 8
`s`	`char[]`	`bytes`	count
`p`	Pascal string	`bytes`	count
`P`	`void*` (native)	`int`	-

A leading count multiplies the next format (e.g. 4i, 10s).

s = Struct('<I H 4s')
buf = s.pack(1, 2, b'abcd')
i, h, b = s.unpack(buf)

Compiled Struct objects are faster for repeated use.

struct.error for malformed format strings, size mismatches, or out-of-range integers.

Area	State
All format characters incl. `e`, `n`/`N`, `P`	Complete.
Byte-order prefixes	Complete.
Native alignment with `@`	Complete; matches the host C compiler layout.
Compiled `Struct` cache	Complete.