Bytes Objects

Python documentation

These functions raise

TypeError

when expecting a bytes parameter and called with a non-bytes parameter.

typePyBytesObject

This subtype of

PyObject

represents a Python bytes object.

PyTypeObject

PyBytes_Type

Part of the

Stable ABI

.This instance of

PyTypeObject

represents the Python bytes type; it is the same object as

bytes

in the Python layer.

intPyBytes_Check(

PyObject

*o)

Return true if the object o is a bytes object or an instance of a subtype of the bytes type. This function always succeeds.

intPyBytes_CheckExact(

PyObject

*o)

Return true if the object o is a bytes object, but not an instance of a subtype of the bytes type. This function always succeeds.

PyObject

*PyBytes_FromString(constchar*v)

Return value: New reference. Part of the

Stable ABI

. Thread safety:

Atomic

.Return a new bytes object with a copy of the string v as value on success, and NULL on failure. The parameter v must not be NULL; it will not be checked.

PyObject

*PyBytes_FromStringAndSize(constchar*v,

Py_ssize_t

len)

Return value: New reference. Part of the

Stable ABI

. Thread safety:

Atomic

.Return a new bytes object with a copy of the string v as value and length len on success, and NULL on failure. If v is NULL, the contents of the bytes object are uninitialized.

PyObject

*PyBytes_FromFormat(constchar*format, ...)

Return value: New reference. Part of the

Stable ABI

. Thread safety:

Atomic

.Take a C printf()-style format string and a variable number of arguments, calculate the size of the resulting Python bytes object and return a bytes object with the values formatted into it. The variable arguments must be C types and must correspond exactly to the format characters in the format string. The following format characters are allowed:

Format Characters

Type

Comment

%%

n/a

The literal % character.

%c

int

A single byte, represented as a C int.

%d

int

Equivalent to printf("%d").

[1]

%u

unsigned int

Equivalent to printf("%u").

[1]

%ld

long

Equivalent to printf("%ld").

[1]

%lu

unsigned long

Equivalent to printf("%lu").

[1]

%zd

Py_ssize_t

Equivalent to printf("%zd").

[1]

%zu

size_t

Equivalent to printf("%zu").

[1]

%i

int

Equivalent to printf("%i").

[1]

%x

int

Equivalent to printf("%x").

[1]

%s

const char*

A null-terminated C character array.

%p

const void*

The hex representation of a C pointer. Mostly equivalent to printf("%p") except that it is guaranteed to start with the literal 0x regardless of what the platform’s printf yields.

An unrecognized format character causes all the rest of the format string to be copied as-is to the result object, and any extra arguments discarded.

PyObject

*PyBytes_FromFormatV(constchar*format, va_listvargs)

Return value: New reference. Part of the

Stable ABI

. Thread safety:

Atomic

.Identical to

PyBytes_FromFormat()

except that it takes exactly two arguments.

PyObject

*PyBytes_FromObject(

PyObject

*o)

Return value: New reference. Part of the

Stable ABI

. Thread safety:

Safe for concurrent use on the same object

.Return the bytes representation of object o that implements the buffer protocol.

Note

If the object implements the buffer protocol, then the buffer must not be mutated while the bytes object is being created.

Py_ssize_t

PyBytes_Size(

PyObject

*o)

Part of the

Stable ABI

. Thread safety:

Atomic

.Return the length of the bytes in bytes object o.

Py_ssize_t

PyBytes_GET_SIZE(

PyObject

*o)

Thread safety:

Atomic

.Similar to

PyBytes_Size()

, but without error checking.

char*PyBytes_AsString(

PyObject

*o)

Part of the

Stable ABI

. Thread safety:

Safe to call from multiple threads with external synchronization only

.Return a pointer to the contents of o. The pointer refers to the internal buffer of o, which consists of len(o)+1 bytes. The last byte in the buffer is always null, regardless of whether there are any other null bytes. The data must not be modified in any way, unless the object was just created using PyBytes_FromStringAndSize(NULL,size). It must not be deallocated. If o is not a bytes object at all,

PyBytes_AsString()

returns NULL and raises

TypeError

.

char*PyBytes_AS_STRING(

PyObject

*string)

Thread safety:

Safe to call from multiple threads with external synchronization only

.Similar to

PyBytes_AsString()

, but without error checking.

intPyBytes_AsStringAndSize(

PyObject

*obj, char**buffer,

Py_ssize_t

*length)

Part of the

Stable ABI

. Thread safety:

Safe to call from multiple threads with external synchronization only

.Return the null-terminated contents of the object obj through the output variables buffer and length. Returns 0 on success.

If length is NULL, the bytes object may not contain embedded null bytes; if it does, the function returns -1 and a

ValueError

is raised.

The buffer refers to an internal buffer of obj, which includes an additional null byte at the end (not counted in length). The data must not be modified in any way, unless the object was just created using PyBytes_FromStringAndSize(NULL,size). It must not be deallocated. If obj is not a bytes object at all,

PyBytes_AsStringAndSize()

returns -1 and raises

TypeError

.

Changed in version 3.5: Previously,

TypeError

was raised when embedded null bytes were encountered in the bytes object.

voidPyBytes_Concat(

PyObject

**bytes,

PyObject

*newpart)

Part of the

Stable ABI

. Thread safety:

Safe for concurrent use on the same object

.Create a new bytes object in *bytes containing the contents of newpart appended to bytes; the caller will own the new reference. The reference to the old value of bytes will be “

stolen

”. If the new object cannot be created, the old reference to bytes will still be “stolen”, the value of *bytes will be set to NULL, and the appropriate exception will be set.

Note

If newpart implements the buffer protocol, then the buffer must not be mutated while the new bytes object is being created.

voidPyBytes_ConcatAndDel(

PyObject

**bytes,

PyObject

*newpart)

Part of the

Stable ABI

. Thread safety:

Safe for concurrent use on the same object

.Create a new bytes object in *bytes containing the contents of newpart appended to bytes. This version releases the

strong reference

to newpart (i.e. decrements its reference count).

Note

If newpart implements the buffer protocol, then the buffer must not be mutated while the new bytes object is being created.

PyObject

*PyBytes_Join(

PyObject

*sep,

PyObject

*iterable)

Thread safety:

Safe for concurrent use on the same object

.Similar to sep.join(iterable) in Python.

sep must be Python

bytes

object. (Note that

PyUnicode_Join()

accepts NULL separator and treats it as a space, whereas

PyBytes_Join()

doesn’t accept NULL separator.)

iterable must be an iterable object yielding objects that implement the

buffer protocol

.

On success, return a new

bytes

object. On error, set an exception and return NULL.

Added in version 3.14.

Note

If iterable objects implement the buffer protocol, then the buffers must not be mutated while the new bytes object is being created.

int_PyBytes_Resize(

PyObject

**bytes,

Py_ssize_t

newsize)

Thread safety:

Safe to call without external synchronization on distinct objects

.Resize a bytes object. newsize will be the new length of the bytes object. You can think of it as creating a new bytes object and destroying the old one, only more efficiently. Pass the address of an existing bytes object as an lvalue (it may be written into), and the new size desired. On success, *bytes holds the resized bytes object and 0 is returned; the address in *bytes may differ from its input value. If the reallocation fails, the original bytes object at *bytes is deallocated, *bytes is set to NULL,

MemoryError

is set, and -1 is returned.

PyObject

*PyBytes_Repr(

PyObject

*bytes, intsmartquotes)

Part of the

Stable ABI

. Thread safety:

Atomic

.Get the string representation of bytes. This function is currently used to implement bytes.__repr__() in Python.

This function does not do type checking; it is undefined behavior to pass bytes as a non-bytes object or NULL.

If smartquotes is true, the representation will use a double-quoted string instead of single-quoted string when single-quotes are present in bytes. For example, the byte string 'Python' would be represented as b"'Python'" when smartquotes is true, or b'\'Python\'' when it is false.

On success, this function returns a

strong reference

to a

str

object containing the representation. On failure, this returns NULL with an exception set.

PyObject

*PyBytes_DecodeEscape(constchar*s,

Py_ssize_t

len, constchar*errors,

Py_ssize_t

unicode, constchar*recode_encoding)

Part of the

Stable ABI

. Thread safety:

Atomic

.Unescape a backslash-escaped string s. s must not be NULL. len must be the size of s.

errors must be one of "strict", "replace", or "ignore". If errors is NULL, then "strict" is used by default.

On success, this function returns a

strong reference

to a Python

bytes

object containing the unescaped string. On failure, this function returns NULL with an exception set.

Changed in version 3.9: unicode and recode_encoding are now unused.