cpython/Doc/c-api/long.rst

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.. highlightlang:: c
.. _longobjects:
Integer Objects
---------------
.. index:: object: long integer
object: integer
All integers are implemented as "long" integer objects of arbitrary size.
.. ctype:: PyLongObject
This subtype of :ctype:`PyObject` represents a Python integer object.
.. cvar:: PyTypeObject PyLong_Type
This instance of :ctype:`PyTypeObject` represents the Python integer type.
This is the same object as ``int``.
.. cfunction:: int PyLong_Check(PyObject *p)
Return true if its argument is a :ctype:`PyLongObject` or a subtype of
:ctype:`PyLongObject`.
.. cfunction:: int PyLong_CheckExact(PyObject *p)
Return true if its argument is a :ctype:`PyLongObject`, but not a subtype of
:ctype:`PyLongObject`.
.. cfunction:: PyObject* PyLong_FromLong(long v)
Return a new :ctype:`PyLongObject` object from *v*, or *NULL* on failure.
The current implementation keeps an array of integer objects for all integers
between ``-5`` and ``256``, when you create an int in that range you actually
just get back a reference to the existing object. So it should be possible to
change the value of ``1``. I suspect the behaviour of Python in this case is
undefined. :-)
.. cfunction:: PyObject* PyLong_FromUnsignedLong(unsigned long v)
Return a new :ctype:`PyLongObject` object from a C :ctype:`unsigned long`, or
*NULL* on failure.
.. cfunction:: PyObject* PyLong_FromSsize_t(Py_ssize_t v)
Return a new :ctype:`PyLongObject` object from a C :ctype:`Py_ssize_t`, or
*NULL* on failure.
.. cfunction:: PyObject* PyLong_FromSize_t(size_t v)
Return a new :ctype:`PyLongObject` object from a C :ctype:`size_t`, or
*NULL* on failure.
.. cfunction:: PyObject* PyLong_FromLongLong(PY_LONG_LONG v)
Return a new :ctype:`PyLongObject` object from a C :ctype:`long long`, or *NULL*
on failure.
.. cfunction:: PyObject* PyLong_FromUnsignedLongLong(unsigned PY_LONG_LONG v)
Return a new :ctype:`PyLongObject` object from a C :ctype:`unsigned long long`,
or *NULL* on failure.
.. cfunction:: PyObject* PyLong_FromDouble(double v)
Return a new :ctype:`PyLongObject` object from the integer part of *v*, or
*NULL* on failure.
.. cfunction:: PyObject* PyLong_FromString(char *str, char **pend, int base)
Return a new :ctype:`PyLongObject` based on the string value in *str*, which
is interpreted according to the radix in *base*. If *pend* is non-*NULL*,
``*pend`` will point to the first character in *str* which follows the
representation of the number. If *base* is ``0``, the radix will be
determined based on the leading characters of *str*: if *str* starts with
``'0x'`` or ``'0X'``, radix 16 will be used; if *str* starts with ``'0o'`` or
``'0O'``, radix 8 will be used; if *str* starts with ``'0b'`` or ``'0B'``,
radix 2 will be used; otherwise radix 10 will be used. If *base* is not
``0``, it must be between ``2`` and ``36``, inclusive. Leading spaces are
ignored. If there are no digits, :exc:`ValueError` will be raised.
.. cfunction:: PyObject* PyLong_FromUnicode(Py_UNICODE *u, Py_ssize_t length, int base)
Convert a sequence of Unicode digits to a Python integer value. The Unicode
string is first encoded to a byte string using :cfunc:`PyUnicode_EncodeDecimal`
and then converted using :cfunc:`PyLong_FromString`.
.. cfunction:: PyObject* PyLong_FromVoidPtr(void *p)
Create a Python integer from the pointer *p*. The pointer value can be
retrieved from the resulting value using :cfunc:`PyLong_AsVoidPtr`.
.. XXX alias PyLong_AS_LONG (for now)
.. cfunction:: long PyLong_AsLong(PyObject *pylong)
.. index::
single: LONG_MAX
single: OverflowError (built-in exception)
Return a C :ctype:`long` representation of the contents of *pylong*. If
*pylong* is greater than :const:`LONG_MAX`, raise an :exc:`OverflowError`,
and return -1. Convert non-long objects automatically to long first,
and return -1 if that raises exceptions.
.. cfunction:: long PyLong_AsLongAndOverflow(PyObject *pylong, int* overflow)
Return a C :ctype:`long` representation of the contents of *pylong*. If
*pylong* is greater than :const:`LONG_MAX`, return -1 and
set `*overflow` to 1 (for overflow) or -1 (for underflow).
If an exception is set because of type errors, also return -1.
.. cfunction:: Py_ssize_t PyLong_AsSsize_t(PyObject *pylong)
.. index::
single: PY_SSIZE_T_MAX
single: OverflowError (built-in exception)
Return a C :ctype:`Py_ssize_t` representation of the contents of *pylong*. If
*pylong* is greater than :const:`PY_SSIZE_T_MAX`, an :exc:`OverflowError` is raised
and ``-1`` will be returned.
.. cfunction:: unsigned long PyLong_AsUnsignedLong(PyObject *pylong)
.. index::
single: ULONG_MAX
single: OverflowError (built-in exception)
Return a C :ctype:`unsigned long` representation of the contents of *pylong*.
If *pylong* is greater than :const:`ULONG_MAX`, an :exc:`OverflowError` is
raised.
.. cfunction:: Py_ssize_t PyLong_AsSsize_t(PyObject *pylong)
.. index::
single: PY_SSIZE_T_MAX
Return a :ctype:`Py_ssize_t` representation of the contents of *pylong*. If
*pylong* is greater than :const:`PY_SSIZE_T_MAX`, an :exc:`OverflowError` is
raised.
.. cfunction:: size_t PyLong_AsSize_t(PyObject *pylong)
Return a :ctype:`size_t` representation of the contents of *pylong*. If
*pylong* is greater than the maximum value for a :ctype:`size_t`, an
:exc:`OverflowError` is raised.
.. cfunction:: PY_LONG_LONG PyLong_AsLongLong(PyObject *pylong)
.. index::
single: OverflowError (built-in exception)
Return a C :ctype:`long long` from a Python integer. If *pylong*
cannot be represented as a :ctype:`long long`, an
:exc:`OverflowError` is raised and ``-1`` is returned.
.. cfunction:: unsigned PY_LONG_LONG PyLong_AsUnsignedLongLong(PyObject *pylong)
.. index::
single: OverflowError (built-in exception)
Return a C :ctype:`unsigned long long` from a Python integer. If
*pylong* cannot be represented as an :ctype:`unsigned long long`,
an :exc:`OverflowError` is raised and ``(unsigned long long)-1`` is
returned.
.. versionchanged:: 3.1
A negative *pylong* now raises :exc:`OverflowError`, not
:exc:`TypeError`.
.. cfunction:: unsigned long PyLong_AsUnsignedLongMask(PyObject *io)
Return a C :ctype:`unsigned long` from a Python integer, without checking for
overflow.
.. cfunction:: unsigned PY_LONG_LONG PyLong_AsUnsignedLongLongMask(PyObject *io)
Return a C :ctype:`unsigned long long` from a Python integer, without
checking for overflow.
.. cfunction:: double PyLong_AsDouble(PyObject *pylong)
Return a C :ctype:`double` representation of the contents of *pylong*. If
*pylong* cannot be approximately represented as a :ctype:`double`, an
:exc:`OverflowError` exception is raised and ``-1.0`` will be returned.
.. cfunction:: void* PyLong_AsVoidPtr(PyObject *pylong)
Convert a Python integer *pylong* to a C :ctype:`void` pointer.
If *pylong* cannot be converted, an :exc:`OverflowError` will be raised. This
is only assured to produce a usable :ctype:`void` pointer for values created
with :cfunc:`PyLong_FromVoidPtr`.