# 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()`.

PyObject *PyLong_FromNativeBytes(const void *buffer, size_t n_bytes, int endianness)

  Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as a two’s-complement signed number.

  endianness may be passed `-1` for the native endian that CPython was compiled with, or else `0` for big endian and `1` for little.

  New in version 3.13.

PyObject *PyLong_FromUnsignedNativeBytes(const void *buffer, size_t n_bytes, int endianness)

  Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as an unsigned number.

  endianness may be passed `-1` for the native endian that CPython was compiled with, or else `0` for big endian and `1` for little.

  New in version 3.13.

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__()`.

int PyLong_AsInt(PyObject *obj)
  Part of the Stable ABI since version 3.13.

  Similar to `PyLong_AsLong()`, but store the result in a C int instead of a C long.

  New in version 3.13.

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.

Py_ssize_t PyLong_AsNativeBytes(PyObject *pylong, void *buffer, Py_ssize_t n_bytes, int endianness)

  Copy the Python integer value to a native buffer of size n_bytes:

      int value;
      Py_ssize_t bytes = PyLong_AsNativeBytes(v, &value, sizeof(value), -1);
      if (bytes < 0) {
          // Error occurred
          return NULL;
      }
      else if (bytes <= (Py_ssize_t)sizeof(value)) {
          // Success!
      }
      else {
          // Overflow occurred, but 'value' contains truncated value
      }

  endianness may be passed `-1` for the native endian that CPython was compiled with, or `0` for big endian and `1` for little.

  Return `-1` with an exception raised if pylong cannot be interpreted as an integer. Otherwise, return the size of the buffer required to store the value. If this is equal to or less than n_bytes, the entire value was copied.

  Unless an exception is raised, all n_bytes of the buffer will be written with as much of the value as can fit. This allows the caller to ignore all non-negative results if the intent is to match the typical behavior of a C-style downcast. No exception is set for this case.

  Values are always copied as two’s-complement, and sufficient buffer will be requested to include a sign bit. For example, this may cause an value that fits into 8 bytes when treated as unsigned to request 9 bytes, even though all eight bytes were copied into the buffer. What has been omitted is the zero sign bit, which is redundant when the intention is to treat the value as unsigned.

  Passing zero to n_bytes will return the requested buffer size.

  Note

  When the value does not fit in the provided buffer, the requested size returned from the function may be larger than necessary. Passing 0 to this function is not an accurate way to determine the bit length of a value.

  New in version 3.13.

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.