:mod:struct -- pack and unpack primitive data types

.. module:: struct :synopsis: pack and unpack primitive data types

|see_cpython_module| :mod:python:struct.

The following byte orders are supported:

+-----------+------------------------+----------+-----------+ | Character | Byte order | Size | Alignment | +===========+========================+==========+===========+ | @ | native | native | native | +-----------+------------------------+----------+-----------+ | < | little-endian | standard | none | +-----------+------------------------+----------+-----------+ | > | big-endian | standard | none | +-----------+------------------------+----------+-----------+ | ! | network (= big-endian) | standard | none | +-----------+------------------------+----------+-----------+

The following data types are supported:

+--------+--------------------+-------------------+---------------+ | Format | C Type | Python type | Standard size | +========+====================+===================+===============+ | b | signed char | integer | 1 | +--------+--------------------+-------------------+---------------+ | B | unsigned char | integer | 1 | +--------+--------------------+-------------------+---------------+ | h | short | integer | 2 | +--------+--------------------+-------------------+---------------+ | H | unsigned short | integer | 2 | +--------+--------------------+-------------------+---------------+ | i | int | integer (1<fn>) | 4 | +--------+--------------------+-------------------+---------------+ | I | unsigned int | integer (1<fn>) | 4 | +--------+--------------------+-------------------+---------------+ | l | long | integer (1<fn>) | 4 | +--------+--------------------+-------------------+---------------+ | L | unsigned long | integer (1<fn>) | 4 | +--------+--------------------+-------------------+---------------+ | q | long long | integer (1<fn>) | 8 | +--------+--------------------+-------------------+---------------+ | Q | unsigned long long | integer (1<fn>) | 8 | +--------+--------------------+-------------------+---------------+ | e | n/a (half-float) | float (2<fn>) | 2 | +--------+--------------------+-------------------+---------------+ | f | float | float (2<fn>) | 4 | +--------+--------------------+-------------------+---------------+ | d | double | float (2<fn>) | 8 | +--------+--------------------+-------------------+---------------+ | s | char[] | bytes | | +--------+--------------------+-------------------+---------------+ | P | void * | integer | | +--------+--------------------+-------------------+---------------+

.. _fn:

(1) Requires long support when used with values larger than 30 bits. (2) Requires floating point support.

.. admonition:: Difference to CPython :class: attention

Whitespace is not supported in format strings.

Functions

.. function:: calcsize(fmt)

Return the number of bytes needed to store the given fmt.

.. function:: pack(fmt, v1, v2, ...)

Pack the values v1, v2, ... according to the format string fmt. The return value is a bytes object encoding the values.

.. function:: pack_into(fmt, buffer, offset, v1, v2, ...)

Pack the values v1, v2, ... according to the format string fmt into a buffer starting at offset. offset may be negative to count from the end of buffer.

.. function:: unpack(fmt, data)

Unpack from the data according to the format string fmt. The return value is a tuple of the unpacked values.

.. function:: unpack_from(fmt, data, offset=0, /)

Unpack from the data starting at offset according to the format string fmt. offset may be negative to count from the end of data. The return value is a tuple of the unpacked values.