API and ABI Versioning

Build-time version constants

CPython exposes its version number in the following macros. Note that these correspond to the version code is built with. See Py_Version for the version used at run time.

See stable for a discussion of API and ABI stability across versions.

The 3 in 3.4.1a2.

The 4 in 3.4.1a2.

The 1 in 3.4.1a2.

The a in 3.4.1a2. This can be 0xA for alpha, 0xB for beta, 0xC for release candidate or 0xF for final.

For completeness, the values are available as macros: !PY_RELEASE_LEVEL_ALPHA (0xA), !PY_RELEASE_LEVEL_BETA (0xB), !PY_RELEASE_LEVEL_GAMMA (0xC), and !PY_RELEASE_LEVEL_FINAL (0xF).

The 2 in 3.4.1a2. Zero for final releases.

The Python version number encoded in a single integer. See Py_PACK_FULL_VERSION for the encoding details.

Use this for numeric comparisons, for example, #if PY_VERSION_HEX >= ....

The Python version as a string, for example, "3.4.1a2".

These macros are defined in Include/patchlevel.h.

Run-time version

The Python runtime version number encoded in a single constant integer. See Py_PACK_FULL_VERSION for the encoding details. This contains the Python version used at run time.

Use this for numeric comparisons, for example, if (Py_Version >= ...).

3.11

Bit-packing macros

Return the given version, encoded as a single 32-bit integer with the following structure:

Argument	No. of bits	Bit mask	Bit shift	Example values
				3.4.1a2	3.10.0
major	8	0xFF000000	24	0x03	0x03
minor	8	0x00FF0000	16	0x04	0x0A
micro	8	0x0000FF00	8	0x01	0x00
release_level	4	0x000000F0	4	0xA	0xF
release_serial	4	0x0000000F	0	0x2	0x0

For example:

Version	Py_PACK_FULL_VERSION arguments	Encoded version
3.4.1a2	(3, 4, 1, 0xA, 2)	0x030401a2
3.10.0	(3, 10, 0, 0xF, 0)	0x030a00f0

Out-of range bits in the arguments are ignored. That is, the macro can be defined as:

#ifndef Py_PACK_FULL_VERSION
#define Py_PACK_FULL_VERSION(X, Y, Z, LEVEL, SERIAL) ( \
   (((X) & 0xff) << 24) |                              \
   (((Y) & 0xff) << 16) |                              \
   (((Z) & 0xff) << 8) |                               \
   (((LEVEL) & 0xf) << 4) |                            \
   (((SERIAL) & 0xf) << 0))
#endif

Py_PACK_FULL_VERSION is primarily a macro, intended for use in #if directives, but it is also available as an exported function.

3.14

Equivalent to Py_PACK_FULL_VERSION(major, minor, 0, 0, 0). The result does not correspond to any Python release, but is useful in numeric comparisons.

3.14