All integers are implemented as “long” integer objects of arbitrary size.
On error, most PyLong_As* APIs return (returntype)-1 which cannot be distinguished from a number. Use
to disambiguate.
typePyLongObject
Part of the
(as an opaque struct).This subtype of
represents a Python integer object.
PyLong_Type
Part of the
.This instance of
represents the Python integer type. This is the same object as
in the Python layer.
intPyLong_Check(
*p)
Return true if its argument is a
or a subtype of PyLongObject. This function always succeeds.
intPyLong_CheckExact(
*p)
Return true if its argument is a
, but not a subtype of PyLongObject. This function always succeeds.
*PyLong_FromLong(longv)
Return value: New reference. Part of the
.Return a new
object from v, or NULL on failure.
CPython implementation detail: CPython 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.
*PyLong_FromUnsignedLong(unsignedlongv)
Return value: New reference. Part of the
.Return a new
object from a C unsignedlong, or NULL on failure.
*PyLong_FromSsize_t(
v)
Return value: New reference. Part of the
.Return a new
object from a C
, or NULL on failure.
*PyLong_FromSize_t(size_tv)
Return value: New reference. Part of the
.Return a new
object from a C size_t, or NULL on failure.
*PyLong_FromLongLong(longlongv)
Return value: New reference. Part of the
.Return a new
object from a C longlong, or NULL on failure.
*PyLong_FromUnsignedLongLong(unsignedlonglongv)
Return value: New reference. Part of the
.Return a new
object from a C unsignedlonglong, or NULL on failure.
*PyLong_FromInt32(int32_tvalue)
*PyLong_FromInt64(int64_tvalue)
Part of the
since version 3.14.Return a new
object from a signed C int32_t or int64_t, or NULL with an exception set on failure.
Added in version 3.14.
*PyLong_FromUInt32(uint32_tvalue)
*PyLong_FromUInt64(uint64_tvalue)
Part of the
since version 3.14.Return a new
object from an unsigned C uint32_t or uint64_t, or NULL with an exception set on failure.
Added in version 3.14.
*PyLong_FromDouble(doublev)
Return value: New reference. Part of the
.Return a new
object from the integer part of v, or NULL on failure.
*PyLong_FromString(constchar*str, char**pend, intbase)
Return value: New reference. Part of the
.Return a new
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
definition; in this case, leading zeros in a non-zero decimal number raises a
. 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
and
functions can be used to convert a
to/from an array of bytes in base 256.
*PyLong_FromUnicodeObject(
*u, intbase)
Return value: New reference.Convert a sequence of Unicode digits in the string u to a Python integer value.
Added in version 3.3.
*PyLong_FromVoidPtr(void*p)
Return value: New reference. Part of the
.Create a Python integer from the pointer p. The pointer value can be retrieved from the resulting value using
.
*PyLong_FromNativeBytes(constvoid*buffer, size_tn_bytes, intflags)
Part of the
since version 3.14.Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as a two’s-complement signed number.
flags are as for
. Passing -1 will select the native endian that CPython was compiled with and assume that the most-significant bit is a sign bit. Passing Py_ASNATIVEBYTES_UNSIGNED_BUFFER will produce the same result as calling
PyLong_FromUnsignedNativeBytes()
. Other flags are ignored.
Added in version 3.13.
*PyLong_FromUnsignedNativeBytes(constvoid*buffer, size_tn_bytes, intflags)
Part of the
since version 3.14.Create a Python integer from the value contained in the first n_bytes of buffer, interpreted as an unsigned number.
flags are as for
. Passing -1 will select the native endian that CPython was compiled with and assume that the most-significant bit is not a sign bit. Flags other than endian are ignored.
Added in version 3.13.
PyLong_FromPid(pid)
Macro for creating a Python integer from a process identifier.
This can be defined as an alias to
or
, depending on the size of the system’s PID type.
Added in version 3.2.
longPyLong_AsLong(
*obj)
Part of the
.Return a C long representation of obj. If obj is not an instance of
, first call its
method (if present) to convert it to a PyLongObject.
Raise
if the value of obj is out of range for a long.
Returns -1 on error. Use
to disambiguate.
Changed in version 3.8: Use
if available.
Changed in version 3.10: This function will no longer use
.
longPyLong_AS_LONG(
*obj)
Exactly equivalent to the preferred PyLong_AsLong. In particular, it can fail with
or another exception.
intPyLong_AsInt(
*obj)
Part of the
since version 3.13.Similar to
, but store the result in a C int instead of a C long.
Added in version 3.13.
longPyLong_AsLongAndOverflow(
*obj, int*overflow)
Part of the
.Return a C long representation of obj. If obj is not an instance of
, first call its
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
to disambiguate.
Changed in version 3.8: Use
if available.
Changed in version 3.10: This function will no longer use
.
longlongPyLong_AsLongLong(
*obj)
Part of the
.Return a C longlong representation of obj. If obj is not an instance of
, first call its
method (if present) to convert it to a PyLongObject.
Raise
if the value of obj is out of range for a longlong.
Returns -1 on error. Use
to disambiguate.
Changed in version 3.8: Use
if available.
Changed in version 3.10: This function will no longer use
.
longlongPyLong_AsLongLongAndOverflow(
*obj, int*overflow)
Part of the
.Return a C longlong representation of obj. If obj is not an instance of
, first call its
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
to disambiguate.
Added in version 3.2.
Changed in version 3.8: Use
if available.
Changed in version 3.10: This function will no longer use
.
PyLong_AsSsize_t(
*pylong)
Part of the
.Return a C
representation of pylong. pylong must be an instance of
.
Raise
if the value of pylong is out of range for a
.
Returns -1 on error. Use
to disambiguate.
unsignedlongPyLong_AsUnsignedLong(
*pylong)
Part of the
.Return a C unsignedlong representation of pylong. pylong must be an instance of
.
Raise
if the value of pylong is out of range for a unsignedlong.
Returns (unsignedlong)-1 on error. Use
to disambiguate.
size_tPyLong_AsSize_t(
*pylong)
Part of the
.Return a C size_t representation of pylong. pylong must be an instance of
.
Raise
if the value of pylong is out of range for a size_t.
Returns (size_t)-1 on error. Use
to disambiguate.
unsignedlonglongPyLong_AsUnsignedLongLong(
*pylong)
Part of the
.Return a C unsignedlonglong representation of pylong. pylong must be an instance of
.
Raise
if the value of pylong is out of range for an unsignedlonglong.
Returns (unsignedlonglong)-1 on error. Use
to disambiguate.
unsignedlongPyLong_AsUnsignedLongMask(
*obj)
Part of the
.Return a C unsignedlong representation of obj. If obj is not an instance of
, first call its
method (if present) to convert it to a PyLongObject.
If the value of obj is out of range for an unsignedlong, return the reduction of that value modulo ULONG_MAX+1.
Returns (unsignedlong)-1 on error. Use
to disambiguate.
Changed in version 3.8: Use
if available.
Changed in version 3.10: This function will no longer use
.
unsignedlonglongPyLong_AsUnsignedLongLongMask(
*obj)
Part of the
.Return a C unsignedlonglong representation of obj. If obj is not an instance of
, first call its
method (if present) to convert it to a PyLongObject.
If the value of obj is out of range for an unsignedlonglong, return the reduction of that value modulo ULLONG_MAX+1.
Returns (unsignedlonglong)-1 on error. Use
to disambiguate.
Changed in version 3.8: Use
if available.
Changed in version 3.10: This function will no longer use
.
intPyLong_AsInt32(
*obj, int32_t*value)
intPyLong_AsInt64(
*obj, int64_t*value)
Part of the
since version 3.14.Set *value to a signed C int32_t or int64_t representation of obj.
If obj is not an instance of
, first call its
method (if present) to convert it to a PyLongObject.
If the obj value is out of range, raise an
.
Set *value and return 0 on success. Set an exception and return -1 on error.
value must not be NULL.
Added in version 3.14.
intPyLong_AsUInt32(
*obj, uint32_t*value)
intPyLong_AsUInt64(
*obj, uint64_t*value)
Part of the
since version 3.14.Set *value to an unsigned C uint32_t or uint64_t representation of obj.
If obj is not an instance of
, first call its
method (if present) to convert it to a PyLongObject.
If obj is negative, raise a
.
If the obj value is out of range, raise an
.
Set *value and return 0 on success. Set an exception and return -1 on error.
value must not be NULL.
Added in version 3.14.
doublePyLong_AsDouble(
*pylong)
Part of the
.Return a C double representation of pylong. pylong must be an instance of
.
Raise
if the value of pylong is out of range for a double.
Returns -1.0 on error. Use
to disambiguate.
void*PyLong_AsVoidPtr(
*pylong)
Part of the
.Convert a Python integer pylong to a C void pointer. If pylong cannot be converted, an
will be raised. This is only assured to produce a usable void pointer for values created with
.
Returns NULL on error. Use
to disambiguate.
PyLong_AsNativeBytes(
*pylong, void*buffer,
n_bytes, intflags)
Part of the
since version 3.14.Copy the Python integer value pylong to a native buffer of size n_bytes. The flags can be set to -1 to behave similarly to a C cast, or to values documented below to control the behavior.
Returns -1 with an exception raised on error. This may happen if pylong cannot be interpreted as an integer, or if pylong was negative and the Py_ASNATIVEBYTES_REJECT_NEGATIVE flag was set.
Otherwise, returns the number of bytes required to store the value. If this is equal to or less than n_bytes, the entire value was copied. All n_bytes of the buffer are written: remaining bytes filled by copies of the sign bit.
If the returned value is greater than n_bytes, the value was truncated: as many of the lowest bits of the value as could fit are written, and the higher bits are ignored. This matches the typical behavior of a C-style downcast.
Note
Overflow is not considered an error. If the returned value is larger than n_bytes, most significant bits were discarded.
0 will never be returned.
Values are always copied as two’s-complement.
Usage example:
int32_tvalue;Py_ssize_tbytes=PyLong_AsNativeBytes(pylong,&value,sizeof(value),-1);if(bytes<0){// Failed. A Python exception was set with the reason.returnNULL;}elseif(bytes<=(Py_ssize_t)sizeof(value)){// Success!}else{// Overflow occurred, but 'value' contains the truncated// lowest bits of pylong.}Passing zero to n_bytes will return the size of a buffer that would be large enough to hold the value. This may be larger than technically necessary, but not unreasonably so. If n_bytes=0, buffer may be NULL.
Note
Passing n_bytes=0 to this function is not an accurate way to determine the bit length of the value.
To get at the entire Python value of an unknown size, the function can be called twice: first to determine the buffer size, then to fill it:
// Ask how much space we need.Py_ssize_texpected=PyLong_AsNativeBytes(pylong,NULL,0,-1);if(expected<0){// Failed. A Python exception was set with the reason.returnNULL;}assert(expected!=0);// Impossible per the API definition.uint8_t*bignum=malloc(expected);if(!bignum){PyErr_SetString(PyExc_MemoryError,"bignum malloc failed.");returnNULL;}// Safely get the entire value.Py_ssize_tbytes=PyLong_AsNativeBytes(pylong,bignum,expected,-1);if(bytes<0){// Exception has been set.free(bignum);returnNULL;}elseif(bytes>expected){// This should not be possible.PyErr_SetString(PyExc_RuntimeError,"Unexpected bignum truncation after a size check.");free(bignum);returnNULL;}// The expected success given the above pre-check.// ... use bignum ...free(bignum);flags is either -1 (Py_ASNATIVEBYTES_DEFAULTS) to select defaults that behave most like a C cast, or a combination of the other flags in the table below. Note that -1 cannot be combined with other flags.
Currently, -1 corresponds to Py_ASNATIVEBYTES_NATIVE_ENDIAN|Py_ASNATIVEBYTES_UNSIGNED_BUFFER.
Flag
Value
Py_ASNATIVEBYTES_DEFAULTS
Part of the
since version 3.14.-1
Py_ASNATIVEBYTES_BIG_ENDIAN
Part of the
since version 3.14.0
Py_ASNATIVEBYTES_LITTLE_ENDIAN
Part of the
since version 3.14.1
Py_ASNATIVEBYTES_NATIVE_ENDIAN
Part of the
since version 3.14.3
Py_ASNATIVEBYTES_UNSIGNED_BUFFER
Part of the
since version 3.14.4
Py_ASNATIVEBYTES_REJECT_NEGATIVE
Part of the
since version 3.14.8
Py_ASNATIVEBYTES_ALLOW_INDEX
Part of the
since version 3.14.16
Specifying Py_ASNATIVEBYTES_NATIVE_ENDIAN will override any other endian flags. Passing 2 is reserved.
By default, sufficient buffer will be requested to include a sign bit. For example, when converting 128 with n_bytes=1, the function will return 2 (or more) in order to store a zero sign bit.
If Py_ASNATIVEBYTES_UNSIGNED_BUFFER is specified, a zero sign bit will be omitted from size calculations. This allows, for example, 128 to fit in a single-byte buffer. If the destination buffer is later treated as signed, a positive input value may become negative. Note that the flag does not affect handling of negative values: for those, space for a sign bit is always requested.
Specifying Py_ASNATIVEBYTES_REJECT_NEGATIVE causes an exception to be set if pylong is negative. Without this flag, negative values will be copied provided there is enough space for at least one sign bit, regardless of whether Py_ASNATIVEBYTES_UNSIGNED_BUFFER was specified.
If Py_ASNATIVEBYTES_ALLOW_INDEX is specified and a non-integer value is passed, its
method will be called first. This may result in Python code executing and other threads being allowed to run, which could cause changes to other objects or values in use. When flags is -1, this option is not set, and non-integer values will raise
.
Note
With the default flags (-1, or UNSIGNED_BUFFER without REJECT_NEGATIVE), multiple Python integers can map to a single value without overflow. For example, both 255 and -1 fit a single-byte buffer and set all its bits. This matches typical C cast behavior.
Added in version 3.13.
PyLong_AsPid(pid)
Macro for converting a Python integer into a process identifier.
This can be defined as an alias to
,
, or
, depending on the size of the system’s PID type.
Added in version 3.2.
intPyLong_GetSign(
*obj, int*sign)
Get the sign of the integer object obj.
On success, set *sign to the integer sign (0, -1 or +1 for zero, negative or positive integer, respectively) and return 0.
On failure, return -1 with an exception set. This function always succeeds if obj is a
or its subtype.
Added in version 3.14.
intPyLong_IsPositive(
*obj)
Check if the integer object obj is positive (obj>0).
If obj is an instance of
or its subtype, return 1 when it’s positive and 0 otherwise. Else set an exception and return -1.
Added in version 3.14.
intPyLong_IsNegative(
*obj)
Check if the integer object obj is negative (obj<0).
If obj is an instance of
or its subtype, return 1 when it’s negative and 0 otherwise. Else set an exception and return -1.
Added in version 3.14.
intPyLong_IsZero(
*obj)
Check if the integer object obj is zero.
If obj is an instance of
or its subtype, return 1 when it’s zero and 0 otherwise. Else set an exception and return -1.
Added in version 3.14.
*PyLong_GetInfo(void)
Part of the
.On success, return a read only
, that holds information about Python’s internal representation of integers. See
for description of individual fields.
On failure, return NULL with an exception set.
Added in version 3.1.
intPyUnstable_Long_IsCompact(const
*op)
This is
. 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
function or
.
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.
Added in version 3.12.
PyUnstable_Long_CompactValue(const
*op)
This is
. It may change without warning in minor releases.
If op is compact, as determined by
, return its value.
Otherwise, the return value is undefined.
Added in version 3.12.
Export API
Added in version 3.14.
structPyLongLayout
Layout of an array of “digits” (“limbs” in the GMP terminology), used to represent absolute value for arbitrary precision integers.
Use
to get the native layout of Python
objects, used internally for integers with “big enough” absolute value.
See also
which exposes similar information in Python.
uint8_tbits_per_digit
Bits per digit. For example, a 15 bit digit means that bits 0-14 contain meaningful information.
uint8_tdigit_size
Digit size in bytes. For example, a 15 bit digit will require at least 2 bytes.
int8_tdigits_order
Digits order:
1 for most significant digit first
-1 for least significant digit first
int8_tdigit_endianness
Digit endianness:
1 for most significant byte first (big endian)
-1 for least significant byte first (little endian)
const
*PyLong_GetNativeLayout(void)
Get the native layout of Python
objects.
See the
structure.
The function must not be called before Python initialization nor after Python finalization. The returned layout is valid until Python is finalized. The layout is the same for all Python sub-interpreters in a process, and so it can be cached.
structPyLongExport
Export of a Python
object.
There are two cases:
If
is NULL, only use the
member.
If
is not NULL, use
,
and digits members.
int64_tvalue
The native integer value of the exported
object. Only valid if
is NULL.
uint8_tnegative
1 if the number is negative, 0 otherwise. Only valid if
is not NULL.
ndigits
Number of digits in
array. Only valid if digits is not NULL.
constvoid*digits
Read-only array of unsigned digits. Can be NULL.
intPyLong_Export(
*obj,
*export_long)
Export a Python
object.
export_long must point to a
structure allocated by the caller. It must not be NULL.
On success, fill in *export_long and return 0. On error, set an exception and return -1.
must be called when the export is no longer needed.
CPython implementation detail: This function always succeeds if obj is a Python
object or a subclass.
voidPyLong_FreeExport(
*export_long)
Release the export export_long created by
.
CPython implementation detail: Calling
is optional if export_long->digits is NULL.
PyLongWriter API
The
API can be used to import an integer.
Added in version 3.14.
structPyLongWriter
A Python
writer instance.
The instance must be destroyed by
or
.
*PyLongWriter_Create(intnegative,
ndigits, void**digits)
Create a
.
On success, allocate *digits and return a writer. On error, set an exception and return NULL.
negative is 1 if the number is negative, or 0 otherwise.
ndigits is the number of digits in the digits array. It must be greater than 0.
digits must not be NULL.
After a successful call to this function, the caller should fill in the array of digits digits and then call
to get a Python
. The layout of digits is described by
.
Digits must be in the range [0; (1<<bits_per_digit)-1] (where the
is the number of bits per digit). Any unused most significant digits must be set to 0.
Alternately, call
to destroy the writer instance without creating an
object.
*PyLongWriter_Finish(
*writer)
Return value: New reference.Finish a
created by
.
On success, return a Python
object. On error, set an exception and return NULL.
The function takes care of normalizing the digits and converts the object to a compact integer if needed.
The writer instance and the digits array are invalid after the call.
voidPyLongWriter_Discard(
*writer)
Discard a
created by
.
If writer is NULL, no operation is performed.
The writer instance and the digits array are invalid after the call.
Deprecated API
These macros are
. They describe parameters of the internal representation of
instances.
Use
instead, along with
to read integer data or
to write it. These currently use the same layout, but are designed to continue working correctly even if CPython’s internal integer representation changes.
PyLong_SHIFT
This is equivalent to
in the output of
.
PyLong_BASE
This is currently equivalent to 1<<
.
PyLong_MASK
This is currently equivalent to (1<<
)-1