mirror of https://github.com/python/cpython
203 lines
9.0 KiB
ReStructuredText
203 lines
9.0 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _bytesobjects:
|
|
|
|
Bytes Objects
|
|
-------------
|
|
|
|
These functions raise :exc:`TypeError` when expecting a bytes parameter and
|
|
called with a non-bytes parameter.
|
|
|
|
.. index:: pair: object; bytes
|
|
|
|
|
|
.. c:type:: PyBytesObject
|
|
|
|
This subtype of :c:type:`PyObject` represents a Python bytes object.
|
|
|
|
|
|
.. c:var:: PyTypeObject PyBytes_Type
|
|
|
|
This instance of :c:type:`PyTypeObject` represents the Python bytes type; it
|
|
is the same object as :class:`bytes` in the Python layer.
|
|
|
|
|
|
.. c:function:: int PyBytes_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.
|
|
|
|
|
|
.. c:function:: int PyBytes_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.
|
|
|
|
|
|
.. c:function:: PyObject* PyBytes_FromString(const char *v)
|
|
|
|
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.
|
|
|
|
|
|
.. c:function:: PyObject* PyBytes_FromStringAndSize(const char *v, Py_ssize_t len)
|
|
|
|
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.
|
|
|
|
|
|
.. c:function:: PyObject* PyBytes_FromFormat(const char *format, ...)
|
|
|
|
Take a C :c:func:`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:
|
|
|
|
.. % XXX: This should be exactly the same as the table in PyErr_Format.
|
|
.. % One should just refer to the other.
|
|
|
|
.. tabularcolumns:: |l|l|L|
|
|
|
|
+-------------------+---------------+--------------------------------+
|
|
| 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`` | :c:type:`\ | Equivalent to |
|
|
| | Py_ssize_t` | ``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.
|
|
|
|
.. [1] For integer specifiers (d, u, ld, lu, zd, zu, i, x): the 0-conversion
|
|
flag has effect even when a precision is given.
|
|
|
|
|
|
.. c:function:: PyObject* PyBytes_FromFormatV(const char *format, va_list vargs)
|
|
|
|
Identical to :c:func:`PyBytes_FromFormat` except that it takes exactly two
|
|
arguments.
|
|
|
|
|
|
.. c:function:: PyObject* PyBytes_FromObject(PyObject *o)
|
|
|
|
Return the bytes representation of object *o* that implements the buffer
|
|
protocol.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyBytes_Size(PyObject *o)
|
|
|
|
Return the length of the bytes in bytes object *o*.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyBytes_GET_SIZE(PyObject *o)
|
|
|
|
Similar to :c:func:`PyBytes_Size`, but without error checking.
|
|
|
|
|
|
.. c:function:: char* PyBytes_AsString(PyObject *o)
|
|
|
|
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, :c:func:`PyBytes_AsString` returns ``NULL``
|
|
and raises :exc:`TypeError`.
|
|
|
|
|
|
.. c:function:: char* PyBytes_AS_STRING(PyObject *string)
|
|
|
|
Similar to :c:func:`PyBytes_AsString`, but without error checking.
|
|
|
|
|
|
.. c:function:: int PyBytes_AsStringAndSize(PyObject *obj, char **buffer, Py_ssize_t *length)
|
|
|
|
Return the null-terminated contents of the object *obj*
|
|
through the output variables *buffer* and *length*.
|
|
|
|
If *length* is ``NULL``, the bytes object
|
|
may not contain embedded null bytes;
|
|
if it does, the function returns ``-1`` and a :exc:`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, :c:func:`PyBytes_AsStringAndSize`
|
|
returns ``-1`` and raises :exc:`TypeError`.
|
|
|
|
.. versionchanged:: 3.5
|
|
Previously, :exc:`TypeError` was raised when embedded null bytes were
|
|
encountered in the bytes object.
|
|
|
|
|
|
.. c:function:: void PyBytes_Concat(PyObject **bytes, PyObject *newpart)
|
|
|
|
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 discarded and the value
|
|
of *\*bytes* will be set to ``NULL``; the appropriate exception will be set.
|
|
|
|
|
|
.. c:function:: void PyBytes_ConcatAndDel(PyObject **bytes, PyObject *newpart)
|
|
|
|
Create a new bytes object in *\*bytes* containing the contents of *newpart*
|
|
appended to *bytes*. This version releases the :term:`strong reference`
|
|
to *newpart* (i.e. decrements its reference count).
|
|
|
|
|
|
.. c:function:: int _PyBytes_Resize(PyObject **bytes, Py_ssize_t newsize)
|
|
|
|
A way to resize a bytes object even though it is "immutable". Only use this
|
|
to build up a brand new bytes object; don't use this if the bytes may already
|
|
be known in other parts of the code. It is an error to call this function if
|
|
the refcount on the input bytes object is not one. 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``, :exc:`MemoryError` is set, and ``-1`` is
|
|
returned.
|