Integer Objects

All integers are implemented as “long” integer objects of arbitrary size.

On error, most PyLong_As* APIs return (return type)-1 which cannot be distinguished from a number. Use PyErr_Occurred() to disambiguate.

type PyLongObject

Part of the Limited API (as an opaque struct).

This subtype of PyObject represents a Python integer object.

PyTypeObject PyLong_Type

Part of the Stable ABI.

This instance of PyTypeObject represents the Python integer type. This is the same object as int in the Python layer.

int PyLong_Check(PyObject *p)

Return true if its argument is a PyLongObject or a subtype of PyLongObject. This function always succeeds.

int PyLong_CheckExact(PyObject *p)

Return true if its argument is a PyLongObject, but not a subtype of PyLongObject. This function always succeeds.

PyObject *PyLong_FromLong(long v)

Return value: New reference. Part of the Stable ABI.

Return a new 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.

PyObject *PyLong_FromUnsignedLong(unsigned long v)

Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C unsigned long, or NULL on failure.

PyObject *PyLong_FromSsize_t(Py_ssize_t v)

Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C Py_ssize_t, or NULL on failure.

PyObject *PyLong_FromSize_t(size_t v)

Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C size_t, or NULL on failure.

PyObject *PyLong_FromLongLong(long long v)

Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C long long, or NULL on failure.

PyObject *PyLong_FromUnsignedLongLong(unsigned long long v)

Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from a C unsigned long long, or NULL on failure.

PyObject *PyLong_FromDouble(double v)

Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject object from the integer part of v, or NULL on failure.

PyObject *PyLong_FromString(const char *str, char **pend, int base)

Return value: New reference. Part of the Stable ABI.

Return a new PyLongObject based on the string value in str, which is interpreted according to the radix in base, or NULL on failure. If pend is non-NULL, *pend will point to the end of str on success or to the first character that could not be processed on error. If base is 0, str is interpreted using the Integer literals definition; in this case, leading zeros in a non-zero decimal number raises a ValueError. If base is not 0, it must be between 2 and 36, inclusive. Leading and trailing whitespace and single underscores after a base specifier and between digits are ignored. If there are no digits or str is not NULL-terminated following the digits and trailing whitespace, ValueError will be raised.

See also

Python methods int.to_bytes() and int.from_bytes() to convert a PyLongObject to/from an array of bytes in base 256. You can call those from C using PyObject_CallMethod().

PyObject *PyLong_FromUnicodeObject(PyObject *u, int base)

Return value: New reference.

Convert a sequence of Unicode digits in the string u to a Python integer value.

New in version 3.3.

PyObject *PyLong_FromVoidPtr(void *p)

Return value: New reference. Part of the Stable ABI.

Create a Python integer from the pointer p. The pointer value can be retrieved from the resulting value using PyLong_AsVoidPtr().

long PyLong_AsLong(PyObject *obj)

Part of the Stable ABI.

Return a C long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

Raise OverflowError if the value of obj is out of range for a long.

Returns -1 on error. Use PyErr_Occurred() to disambiguate.

Changed in version 3.8: Use __index__() if available.

Changed in version 3.10: This function will no longer use __int__().

long PyLong_AsLongAndOverflow(PyObject *obj, int *overflow)

Part of the Stable ABI.

Return a C long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is greater than LONG_MAX or less than LONG_MIN, set *overflow to 1 or -1, respectively, and return -1; otherwise, set *overflow to 0. If any other exception occurs set *overflow to 0 and return -1 as usual.

Returns -1 on error. Use PyErr_Occurred() to disambiguate.

Changed in version 3.8: Use __index__() if available.

Changed in version 3.10: This function will no longer use __int__().

long long PyLong_AsLongLong(PyObject *obj)

Part of the Stable ABI.

Return a C long long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

Raise OverflowError if the value of obj is out of range for a long long.

Returns -1 on error. Use PyErr_Occurred() to disambiguate.

Changed in version 3.8: Use __index__() if available.

Changed in version 3.10: This function will no longer use __int__().

long long PyLong_AsLongLongAndOverflow(PyObject *obj, int *overflow)

Part of the Stable ABI.

Return a C long long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is greater than LLONG_MAX or less than LLONG_MIN, set *overflow to 1 or -1, respectively, and return -1; otherwise, set *overflow to 0. If any other exception occurs set *overflow to 0 and return -1 as usual.

Returns -1 on error. Use PyErr_Occurred() to disambiguate.

New in version 3.2.

Changed in version 3.8: Use __index__() if available.

Changed in version 3.10: This function will no longer use __int__().

Py_ssize_t PyLong_AsSsize_t(PyObject *pylong)

Part of the Stable ABI.

Return a C Py_ssize_t representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for a Py_ssize_t.

Returns -1 on error. Use PyErr_Occurred() to disambiguate.

unsigned long PyLong_AsUnsignedLong(PyObject *pylong)

Part of the Stable ABI.

Return a C unsigned long representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for a unsigned long.

Returns (unsigned long)-1 on error. Use PyErr_Occurred() to disambiguate.

size_t PyLong_AsSize_t(PyObject *pylong)

Part of the Stable ABI.

Return a C size_t representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for a size_t.

Returns (size_t)-1 on error. Use PyErr_Occurred() to disambiguate.

unsigned long long PyLong_AsUnsignedLongLong(PyObject *pylong)

Part of the Stable ABI.

Return a C unsigned long long representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for an unsigned long long.

Returns (unsigned long long)-1 on error. Use PyErr_Occurred() to disambiguate.

Changed in version 3.1: A negative pylong now raises OverflowError, not TypeError.

unsigned long PyLong_AsUnsignedLongMask(PyObject *obj)

Part of the Stable ABI.

Return a C unsigned long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is out of range for an unsigned long, return the reduction of that value modulo ULONG_MAX + 1.

Returns (unsigned long)-1 on error. Use PyErr_Occurred() to disambiguate.

Changed in version 3.8: Use __index__() if available.

Changed in version 3.10: This function will no longer use __int__().

unsigned long long PyLong_AsUnsignedLongLongMask(PyObject *obj)

Part of the Stable ABI.

Return a C unsigned long long representation of obj. If obj is not an instance of PyLongObject, first call its __index__() method (if present) to convert it to a PyLongObject.

If the value of obj is out of range for an unsigned long long, return the reduction of that value modulo ULLONG_MAX + 1.

Returns (unsigned long long)-1 on error. Use PyErr_Occurred() to disambiguate.

Changed in version 3.8: Use __index__() if available.

Changed in version 3.10: This function will no longer use __int__().

double PyLong_AsDouble(PyObject *pylong)

Part of the Stable ABI.

Return a C double representation of pylong. pylong must be an instance of PyLongObject.

Raise OverflowError if the value of pylong is out of range for a double.

Returns -1.0 on error. Use PyErr_Occurred() to disambiguate.

void *PyLong_AsVoidPtr(PyObject *pylong)

Part of the Stable ABI.

Convert a Python integer pylong to a C void pointer. If pylong cannot be converted, an OverflowError will be raised. This is only assured to produce a usable void pointer for values created with PyLong_FromVoidPtr().

Returns NULL on error. Use PyErr_Occurred() to disambiguate.

int PyUnstable_Long_IsCompact(const PyLongObject *op)

This is Unstable API. It may change without warning in minor releases.

Return 1 if op is compact, 0 otherwise.

This function makes it possible for performance-critical code to implement a “fast path” for small integers. For compact values use PyUnstable_Long_CompactValue(); for others fall back to a PyLong_As* function or calling int.to_bytes().

The speedup is expected to be negligible for most users.

Exactly what values are considered compact is an implementation detail and is subject to change.

Py_ssize_t PyUnstable_Long_CompactValue(const PyLongObject *op)

This is Unstable API. It may change without warning in minor releases.

If op is compact, as determined by PyUnstable_Long_IsCompact(), return its value.

Otherwise, the return value is undefined.