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gh-141004: Document Py_ARRAY_LENGTH macro #141598

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gh-141004: Document Py_ARRAY_LENGTH macro #141598

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gh-141004: Document Py_ARRAY_LENGTH macro
Yashp002 Nov 15, 2025
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Move Py_ARRAY_LENGTH to Useful macros, use 'generally equivalent'
Yashp002 Nov 15, 2025
d96374e
Move Py_ARRAY_LENGTH to Useful macros, use 'generally equivalent'
Yashp002 Nov 15, 2025
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15 changes: 15 additions & 0 deletions Doc/c-api/structures.rst
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Expand Up @@ -730,6 +730,21 @@ Macro name C type Python type

Always ``None``. Must be used with :c:macro:`Py_READONLY`.

.. c:macro:: Py_ARRAY_LENGTH(array)

Compute the length (number of elements) of a statically allocated C array at
compile time.

The *array* argument must be a C array with a size known at compile time,
not a pointer. Using this macro with a pointer will produce incorrect results.

This macro is defined as::

#define Py_ARRAY_LENGTH(array) (sizeof(array) / sizeof((array)[0]))
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@StanFromIreland StanFromIreland Nov 15, 2025

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Technically, this is wrong since depending on the GCC version it varies.

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@ZeroIntensity ZeroIntensity Nov 15, 2025

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Yeah, let's just say something like "This is generally equivalent to ..."


.. versionadded:: 3.13
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@StanFromIreland StanFromIreland Nov 15, 2025 •
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This is wrong, it has been around for many years (2.7 & before).



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@StanFromIreland StanFromIreland Nov 15, 2025

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Suggested change

Unrelated changes.

Defining Getters and Setters
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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