Unicode Type

These are the basic Unicode object types used for the Unicode implementation in Python:

Py_UNICODE

This type represents the storage type which is used by Python internally as basis for holding Unicode ordinals. Python’s default builds use a 16-bit type for Py_UNICODE and store Unicode values internally as UCS2. It is also possible to build a UCS4 version of Python (most recent Linux distributions come with UCS4 builds of Python). These builds then use a 32-bit type for Py_UNICODE and store Unicode data internally as UCS4. On platforms where wchar_t is available and compatible with the chosen Python Unicode build variant, Py_UNICODE is a typedef alias for wchar_t to enhance native platform compatibility. On all other platforms, Py_UNICODE is a typedef alias for either unsigned short (UCS2) or unsigned long (UCS4).

Note that UCS2 and UCS4 Python builds are not binary compatible. Please keep this in mind when writing extensions or interfaces.

PyUnicodeObject

This subtype of PyObject represents a Python Unicode object.

PyTypeObject PyUnicode_Type

This instance of PyTypeObject represents the Python Unicode type. It is exposed to Python code as unicode and types.UnicodeType.

The following APIs are really C macros and can be used to do fast checks and to access internal read-only data of Unicode objects:

int PyUnicode_Check(PyObject *o)

Return true if the object o is a Unicode object or an instance of a Unicode subtype.

Changed in version 2.2: Allowed subtypes to be accepted.

int PyUnicode_CheckExact(PyObject *o)

Return true if the object o is a Unicode object, but not an instance of a subtype.

New in version 2.2.

Py_ssize_t PyUnicode_GET_SIZE(PyObject *o)

Return the size of the object. o has to be a PyUnicodeObject (not checked).

Changed in version 2.5: This function returned an int type. This might require changes in your code for properly supporting 64-bit systems.

Py_ssize_t PyUnicode_GET_DATA_SIZE(PyObject *o)

Return the size of the object’s internal buffer in bytes. o has to be a PyUnicodeObject (not checked).

Changed in version 2.5: This function returned an int type. This might require changes in your code for properly supporting 64-bit systems.

Py_UNICODE* PyUnicode_AS_UNICODE(PyObject *o)

Return a pointer to the internal Py_UNICODE buffer of the object. o has to be a PyUnicodeObject (not checked).

const char* PyUnicode_AS_DATA(PyObject *o)

Return a pointer to the internal buffer of the object. o has to be a PyUnicodeObject (not checked).

int PyUnicode_ClearFreeList()

Clear the free list. Return the total number of freed items.

New in version 2.6.

Unicode Character Properties

Unicode provides many different character properties. The most often needed ones are available through these macros which are mapped to C functions depending on the Python configuration.

int Py_UNICODE_ISSPACE(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is a whitespace character.

int Py_UNICODE_ISLOWER(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is a lowercase character.

int Py_UNICODE_ISUPPER(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is an uppercase character.

int Py_UNICODE_ISTITLE(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is a titlecase character.

int Py_UNICODE_ISLINEBREAK(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is a linebreak character.

int Py_UNICODE_ISDECIMAL(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is a decimal character.

int Py_UNICODE_ISDIGIT(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is a digit character.

int Py_UNICODE_ISNUMERIC(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is a numeric character.

int Py_UNICODE_ISALPHA(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is an alphabetic character.

int Py_UNICODE_ISALNUM(Py_UNICODE ch)

Return 1 or 0 depending on whether ch is an alphanumeric character.

These APIs can be used for fast direct character conversions:

Py_UNICODE Py_UNICODE_TOLOWER(Py_UNICODE ch)

Return the character ch converted to lower case.

Py_UNICODE Py_UNICODE_TOUPPER(Py_UNICODE ch)

Return the character ch converted to upper case.

Py_UNICODE Py_UNICODE_TOTITLE(Py_UNICODE ch)

Return the character ch converted to title case.

int Py_UNICODE_TODECIMAL(Py_UNICODE ch)

Return the character ch converted to a decimal positive integer. Return -1 if this is not possible. This macro does not raise exceptions.

int Py_UNICODE_TODIGIT(Py_UNICODE ch)

Return the character ch converted to a single digit integer. Return -1 if this is not possible. This macro does not raise exceptions.

double Py_UNICODE_TONUMERIC(Py_UNICODE ch)

Return the character ch converted to a double. Return -1.0 if this is not possible. This macro does not raise exceptions.

Plain Py_UNICODE

To create Unicode objects and access their basic sequence properties, use these APIs:

PyObject* PyUnicode_FromUnicode(const Py_UNICODE *u, Py_ssize_t size)

Return value: New reference.

Create a Unicode Object from the Py_UNICODE buffer u of the given size. u may be NULL which causes the contents to be undefined. It is the user’s responsibility to fill in the needed data. The buffer is copied into the new object. If the buffer is not NULL, the return value might be a shared object. Therefore, modification of the resulting Unicode object is only allowed when u is NULL.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

Py_UNICODE* PyUnicode_AsUnicode(PyObject *unicode)

Return a read-only pointer to the Unicode object’s internal Py_UNICODE buffer, NULL if unicode is not a Unicode object.

Py_ssize_t PyUnicode_GetSize(PyObject *unicode)

Return the length of the Unicode object.

Changed in version 2.5: This function returned an int type. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_FromEncodedObject(PyObject *obj, const char *encoding, const char *errors)

Return value: New reference.

Coerce an encoded object obj to an Unicode object and return a reference with incremented refcount.

String and other char buffer compatible objects are decoded according to the given encoding and using the error handling defined by errors. Both can be NULL to have the interface use the default values (see the next section for details).

All other objects, including Unicode objects, cause a TypeError to be set.

The API returns NULL if there was an error. The caller is responsible for decref’ing the returned objects.

PyObject* PyUnicode_FromObject(PyObject *obj)

Return value: New reference.

Shortcut for PyUnicode_FromEncodedObject(obj, NULL, "strict") which is used throughout the interpreter whenever coercion to Unicode is needed.

If the platform supports wchar_t and provides a header file wchar.h, Python can interface directly to this type using the following functions. Support is optimized if Python’s own Py_UNICODE type is identical to the system’s wchar_t.

wchar_t Support

wchar_t support for platforms which support it:

PyObject* PyUnicode_FromWideChar(const wchar_t *w, Py_ssize_t size)

Return value: New reference.

Create a Unicode object from the wchar_t buffer w of the given size. Return NULL on failure.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

Py_ssize_t PyUnicode_AsWideChar(PyUnicodeObject *unicode, wchar_t *w, Py_ssize_t size)

Copy the Unicode object contents into the wchar_t buffer w. At most size wchar_t characters are copied (excluding a possibly trailing 0-termination character). Return the number of wchar_t characters copied or -1 in case of an error. Note that the resulting wchar_t string may or may not be 0-terminated. It is the responsibility of the caller to make sure that the wchar_t string is 0-terminated in case this is required by the application.

Changed in version 2.5: This function returned an int type and used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

Generic Codecs

These are the generic codec APIs:

PyObject* PyUnicode_Decode(const char *s, Py_ssize_t size, const char *encoding, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the encoded string s. encoding and errors have the same meaning as the parameters of the same name in the unicode() built-in function. The codec to be used is looked up using the Python codec registry. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_Encode(const Py_UNICODE *s, Py_ssize_t size, const char *encoding, const char *errors)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size and return a Python string object. encoding and errors have the same meaning as the parameters of the same name in the Unicode encode() method. The codec to be used is looked up using the Python codec registry. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsEncodedString(PyObject *unicode, const char *encoding, const char *errors)

Return value: New reference.

Encode a Unicode object and return the result as Python string object. encoding and errors have the same meaning as the parameters of the same name in the Unicode encode() method. The codec to be used is looked up using the Python codec registry. Return NULL if an exception was raised by the codec.

UTF-8 Codecs

These are the UTF-8 codec APIs:

PyObject* PyUnicode_DecodeUTF8(const char *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the UTF-8 encoded string s. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_DecodeUTF8Stateful(const char *s, Py_ssize_t size, const char *errors, Py_ssize_t *consumed)

Return value: New reference.

If consumed is NULL, behave like PyUnicode_DecodeUTF8(). If consumed is not NULL, trailing incomplete UTF-8 byte sequences will not be treated as an error. Those bytes will not be decoded and the number of bytes that have been decoded will be stored in consumed.

New in version 2.4.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_EncodeUTF8(const Py_UNICODE *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size using UTF-8 and return a Python string object. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsUTF8String(PyObject *unicode)

Return value: New reference.

Encode a Unicode object using UTF-8 and return the result as Python string object. Error handling is “strict”. Return NULL if an exception was raised by the codec.

UTF-32 Codecs

These are the UTF-32 codec APIs:

PyObject* PyUnicode_DecodeUTF32(const char *s, Py_ssize_t size, const char *errors, int *byteorder)

Decode length bytes from a UTF-32 encoded buffer string and return the corresponding Unicode object. errors (if non-NULL) defines the error handling. It defaults to “strict”.

If byteorder is non-NULL, the decoder starts decoding using the given byte order:

*byteorder == -1: little endian
*byteorder == 0:  native order
*byteorder == 1:  big endian

If *byteorder is zero, and the first four bytes of the input data are a byte order mark (BOM), the decoder switches to this byte order and the BOM is not copied into the resulting Unicode string. If *byteorder is -1 or 1, any byte order mark is copied to the output.

After completion, *byteorder is set to the current byte order at the end of input data.

In a narrow build codepoints outside the BMP will be decoded as surrogate pairs.

If byteorder is NULL, the codec starts in native order mode.

Return NULL if an exception was raised by the codec.

New in version 2.6.

PyObject* PyUnicode_DecodeUTF32Stateful(const char *s, Py_ssize_t size, const char *errors, int *byteorder, Py_ssize_t *consumed)

If consumed is NULL, behave like PyUnicode_DecodeUTF32(). If consumed is not NULL, PyUnicode_DecodeUTF32Stateful() will not treat trailing incomplete UTF-32 byte sequences (such as a number of bytes not divisible by four) as an error. Those bytes will not be decoded and the number of bytes that have been decoded will be stored in consumed.

New in version 2.6.

PyObject* PyUnicode_EncodeUTF32(const Py_UNICODE *s, Py_ssize_t size, const char *errors, int byteorder)

Return a Python bytes object holding the UTF-32 encoded value of the Unicode data in s. Output is written according to the following byte order:

byteorder == -1: little endian
byteorder == 0:  native byte order (writes a BOM mark)
byteorder == 1:  big endian

If byteorder is 0, the output string will always start with the Unicode BOM mark (U+FEFF). In the other two modes, no BOM mark is prepended.

If Py_UNICODE_WIDE is not defined, surrogate pairs will be output as a single codepoint.

Return NULL if an exception was raised by the codec.

New in version 2.6.

PyObject* PyUnicode_AsUTF32String(PyObject *unicode)

Return a Python string using the UTF-32 encoding in native byte order. The string always starts with a BOM mark. Error handling is “strict”. Return NULL if an exception was raised by the codec.

New in version 2.6.

UTF-16 Codecs

These are the UTF-16 codec APIs:

PyObject* PyUnicode_DecodeUTF16(const char *s, Py_ssize_t size, const char *errors, int *byteorder)

Return value: New reference.

Decode length bytes from a UTF-16 encoded buffer string and return the corresponding Unicode object. errors (if non-NULL) defines the error handling. It defaults to “strict”.

If byteorder is non-NULL, the decoder starts decoding using the given byte order:

*byteorder == -1: little endian
*byteorder == 0:  native order
*byteorder == 1:  big endian

If *byteorder is zero, and the first two bytes of the input data are a byte order mark (BOM), the decoder switches to this byte order and the BOM is not copied into the resulting Unicode string. If *byteorder is -1 or 1, any byte order mark is copied to the output (where it will result in either a \ufeff or a \ufffe character).

After completion, *byteorder is set to the current byte order at the end of input data.

If byteorder is NULL, the codec starts in native order mode.

Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_DecodeUTF16Stateful(const char *s, Py_ssize_t size, const char *errors, int *byteorder, Py_ssize_t *consumed)

Return value: New reference.

If consumed is NULL, behave like PyUnicode_DecodeUTF16(). If consumed is not NULL, PyUnicode_DecodeUTF16Stateful() will not treat trailing incomplete UTF-16 byte sequences (such as an odd number of bytes or a split surrogate pair) as an error. Those bytes will not be decoded and the number of bytes that have been decoded will be stored in consumed.

New in version 2.4.

Changed in version 2.5: This function used an int type for size and an int * type for consumed. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_EncodeUTF16(const Py_UNICODE *s, Py_ssize_t size, const char *errors, int byteorder)

Return value: New reference.

Return a Python string object holding the UTF-16 encoded value of the Unicode data in s. Output is written according to the following byte order:

byteorder == -1: little endian
byteorder == 0:  native byte order (writes a BOM mark)
byteorder == 1:  big endian

If byteorder is 0, the output string will always start with the Unicode BOM mark (U+FEFF). In the other two modes, no BOM mark is prepended.

If Py_UNICODE_WIDE is defined, a single Py_UNICODE value may get represented as a surrogate pair. If it is not defined, each Py_UNICODE values is interpreted as an UCS-2 character.

Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsUTF16String(PyObject *unicode)

Return value: New reference.

Return a Python string using the UTF-16 encoding in native byte order. The string always starts with a BOM mark. Error handling is “strict”. Return NULL if an exception was raised by the codec.

Unicode-Escape Codecs

These are the “Unicode Escape” codec APIs:

PyObject* PyUnicode_DecodeUnicodeEscape(const char *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the Unicode-Escape encoded string s. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_EncodeUnicodeEscape(const Py_UNICODE *s, Py_ssize_t size)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size using Unicode-Escape and return a Python string object. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsUnicodeEscapeString(PyObject *unicode)

Return value: New reference.

Encode a Unicode object using Unicode-Escape and return the result as Python string object. Error handling is “strict”. Return NULL if an exception was raised by the codec.

Raw-Unicode-Escape Codecs

These are the “Raw Unicode Escape” codec APIs:

PyObject* PyUnicode_DecodeRawUnicodeEscape(const char *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the Raw-Unicode-Escape encoded string s. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_EncodeRawUnicodeEscape(const Py_UNICODE *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size using Raw-Unicode-Escape and return a Python string object. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsRawUnicodeEscapeString(PyObject *unicode)

Return value: New reference.

Encode a Unicode object using Raw-Unicode-Escape and return the result as Python string object. Error handling is “strict”. Return NULL if an exception was raised by the codec.

Latin-1 Codecs

These are the Latin-1 codec APIs: Latin-1 corresponds to the first 256 Unicode ordinals and only these are accepted by the codecs during encoding.

PyObject* PyUnicode_DecodeLatin1(const char *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the Latin-1 encoded string s. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_EncodeLatin1(const Py_UNICODE *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size using Latin-1 and return a Python string object. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsLatin1String(PyObject *unicode)

Return value: New reference.

Encode a Unicode object using Latin-1 and return the result as Python string object. Error handling is “strict”. Return NULL if an exception was raised by the codec.

ASCII Codecs

These are the ASCII codec APIs. Only 7-bit ASCII data is accepted. All other codes generate errors.

PyObject* PyUnicode_DecodeASCII(const char *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the ASCII encoded string s. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_EncodeASCII(const Py_UNICODE *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size using ASCII and return a Python string object. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsASCIIString(PyObject *unicode)

Return value: New reference.

Encode a Unicode object using ASCII and return the result as Python string object. Error handling is “strict”. Return NULL if an exception was raised by the codec.

Character Map Codecs

These are the mapping codec APIs:

This codec is special in that it can be used to implement many different codecs (and this is in fact what was done to obtain most of the standard codecs included in the encodings package). The codec uses mapping to encode and decode characters.

Decoding mappings must map single string characters to single Unicode characters, integers (which are then interpreted as Unicode ordinals) or None (meaning “undefined mapping” and causing an error).

Encoding mappings must map single Unicode characters to single string characters, integers (which are then interpreted as Latin-1 ordinals) or None (meaning “undefined mapping” and causing an error).

The mapping objects provided must only support the __getitem__ mapping interface.

If a character lookup fails with a LookupError, the character is copied as-is meaning that its ordinal value will be interpreted as Unicode or Latin-1 ordinal resp. Because of this, mappings only need to contain those mappings which map characters to different code points.

PyObject* PyUnicode_DecodeCharmap(const char *s, Py_ssize_t size, PyObject *mapping, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the encoded string s using the given mapping object. Return NULL if an exception was raised by the codec. If mapping is NULL latin-1 decoding will be done. Else it can be a dictionary mapping byte or a unicode string, which is treated as a lookup table. Byte values greater that the length of the string and U+FFFE “characters” are treated as “undefined mapping”.

Changed in version 2.4: Allowed unicode string as mapping argument.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_EncodeCharmap(const Py_UNICODE *s, Py_ssize_t size, PyObject *mapping, const char *errors)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size using the given mapping object and return a Python string object. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsCharmapString(PyObject *unicode, PyObject *mapping)

Return value: New reference.

Encode a Unicode object using the given mapping object and return the result as Python string object. Error handling is “strict”. Return NULL if an exception was raised by the codec.

The following codec API is special in that maps Unicode to Unicode.

PyObject* PyUnicode_TranslateCharmap(const Py_UNICODE *s, Py_ssize_t size, PyObject *table, const char *errors)

Return value: New reference.

Translate a Py_UNICODE buffer of the given length by applying a character mapping table to it and return the resulting Unicode object. Return NULL when an exception was raised by the codec.

The mapping table must map Unicode ordinal integers to Unicode ordinal integers or None (causing deletion of the character).

Mapping tables need only provide the __getitem__() interface; dictionaries and sequences work well. Unmapped character ordinals (ones which cause a LookupError) are left untouched and are copied as-is.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

These are the MBCS codec APIs. They are currently only available on Windows and use the Win32 MBCS converters to implement the conversions. Note that MBCS (or DBCS) is a class of encodings, not just one. The target encoding is defined by the user settings on the machine running the codec.

MBCS codecs for Windows

PyObject* PyUnicode_DecodeMBCS(const char *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Create a Unicode object by decoding size bytes of the MBCS encoded string s. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_DecodeMBCSStateful(const char *s, int size, const char *errors, int *consumed)

If consumed is NULL, behave like PyUnicode_DecodeMBCS(). If consumed is not NULL, PyUnicode_DecodeMBCSStateful() will not decode trailing lead byte and the number of bytes that have been decoded will be stored in consumed.

New in version 2.5.

PyObject* PyUnicode_EncodeMBCS(const Py_UNICODE *s, Py_ssize_t size, const char *errors)

Return value: New reference.

Encode the Py_UNICODE buffer of the given size using MBCS and return a Python string object. Return NULL if an exception was raised by the codec.

Changed in version 2.5: This function used an int type for size. This might require changes in your code for properly supporting 64-bit systems.

PyObject* PyUnicode_AsMBCSString(PyObject *unicode)

Return value: New reference.

Encode a Unicode object using MBCS and return the result as Python string object. Error handling is “strict”. Return NULL if an exception was raised by the codec.

Methods & Slots