95 lines
4.2 KiB
ReStructuredText
95 lines
4.2 KiB
ReStructuredText
:mod:`struct` -- pack and unpack primitive data types
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=====================================================
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.. module:: struct
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:synopsis: pack and unpack primitive data types
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|see_cpython_module| :mod:`python:struct`.
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The following byte orders are supported:
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+-----------+------------------------+----------+-----------+
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| Character | Byte order | Size | Alignment |
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+===========+========================+==========+===========+
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| @ | native | native | native |
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+-----------+------------------------+----------+-----------+
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| < | little-endian | standard | none |
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+-----------+------------------------+----------+-----------+
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| > | big-endian | standard | none |
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+-----------+------------------------+----------+-----------+
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| ! | network (= big-endian) | standard | none |
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+-----------+------------------------+----------+-----------+
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The following data types are supported:
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+--------+--------------------+-------------------+---------------+
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| Format | C Type | Python type | Standard size |
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+========+====================+===================+===============+
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| b | signed char | integer | 1 |
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+--------+--------------------+-------------------+---------------+
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| B | unsigned char | integer | 1 |
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+--------+--------------------+-------------------+---------------+
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| h | short | integer | 2 |
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+--------+--------------------+-------------------+---------------+
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| H | unsigned short | integer | 2 |
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+--------+--------------------+-------------------+---------------+
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| i | int | integer (`1<fn>`) | 4 |
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+--------+--------------------+-------------------+---------------+
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| I | unsigned int | integer (`1<fn>`) | 4 |
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+--------+--------------------+-------------------+---------------+
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| l | long | integer (`1<fn>`) | 4 |
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+--------+--------------------+-------------------+---------------+
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| L | unsigned long | integer (`1<fn>`) | 4 |
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+--------+--------------------+-------------------+---------------+
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| q | long long | integer (`1<fn>`) | 8 |
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+--------+--------------------+-------------------+---------------+
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| Q | unsigned long long | integer (`1<fn>`) | 8 |
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+--------+--------------------+-------------------+---------------+
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| f | float | float (`2<fn>`) | 4 |
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+--------+--------------------+-------------------+---------------+
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| d | double | float (`2<fn>`) | 8 |
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+--------+--------------------+-------------------+---------------+
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| s | char[] | bytes | |
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+--------+--------------------+-------------------+---------------+
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| P | void * | integer | |
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+--------+--------------------+-------------------+---------------+
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.. _fn:
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(1) Requires long support when used with values larger than 30 bits.
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(2) Requires floating point support.
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.. admonition:: Difference to CPython
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:class: attention
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Whitespace is not supported in format strings.
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Functions
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---------
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.. function:: calcsize(fmt)
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Return the number of bytes needed to store the given *fmt*.
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.. function:: pack(fmt, v1, v2, ...)
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Pack the values *v1*, *v2*, ... according to the format string *fmt*.
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The return value is a bytes object encoding the values.
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.. function:: pack_into(fmt, buffer, offset, v1, v2, ...)
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Pack the values *v1*, *v2*, ... according to the format string *fmt*
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into a *buffer* starting at *offset*. *offset* may be negative to count
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from the end of *buffer*.
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.. function:: unpack(fmt, data)
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Unpack from the *data* according to the format string *fmt*.
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The return value is a tuple of the unpacked values.
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.. function:: unpack_from(fmt, data, offset=0, /)
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Unpack from the *data* starting at *offset* according to the format string
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*fmt*. *offset* may be negative to count from the end of *data*. The return
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value is a tuple of the unpacked values.
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