1 .. highlightlang:: c 2 3 .. _bytesobjects: 4 5 Bytes Objects 6 ------------- 7 8 These functions raise :exc:`TypeError` when expecting a bytes parameter and are 9 called with a non-bytes parameter. 10 11 .. index:: object: bytes 12 13 14 .. c:type:: PyBytesObject 15 16 This subtype of :c:type:`PyObject` represents a Python bytes object. 17 18 19 .. c:var:: PyTypeObject PyBytes_Type 20 21 This instance of :c:type:`PyTypeObject` represents the Python bytes type; it 22 is the same object as :class:`bytes` in the Python layer. 23 24 25 .. c:function:: int PyBytes_Check(PyObject *o) 26 27 Return true if the object *o* is a bytes object or an instance of a subtype 28 of the bytes type. 29 30 31 .. c:function:: int PyBytes_CheckExact(PyObject *o) 32 33 Return true if the object *o* is a bytes object, but not an instance of a 34 subtype of the bytes type. 35 36 37 .. c:function:: PyObject* PyBytes_FromString(const char *v) 38 39 Return a new bytes object with a copy of the string *v* as value on success, 40 and *NULL* on failure. The parameter *v* must not be *NULL*; it will not be 41 checked. 42 43 44 .. c:function:: PyObject* PyBytes_FromStringAndSize(const char *v, Py_ssize_t len) 45 46 Return a new bytes object with a copy of the string *v* as value and length 47 *len* on success, and *NULL* on failure. If *v* is *NULL*, the contents of 48 the bytes object are uninitialized. 49 50 51 .. c:function:: PyObject* PyBytes_FromFormat(const char *format, ...) 52 53 Take a C :c:func:`printf`\ -style *format* string and a variable number of 54 arguments, calculate the size of the resulting Python bytes object and return 55 a bytes object with the values formatted into it. The variable arguments 56 must be C types and must correspond exactly to the format characters in the 57 *format* string. The following format characters are allowed: 58 59 .. % XXX: This should be exactly the same as the table in PyErr_Format. 60 .. % One should just refer to the other. 61 .. % XXX: The descriptions for %zd and %zu are wrong, but the truth is complicated 62 .. % because not all compilers support the %z width modifier -- we fake it 63 .. % when necessary via interpolating PY_FORMAT_SIZE_T. 64 65 .. tabularcolumns:: |l|l|L| 66 67 +-------------------+---------------+--------------------------------+ 68 | Format Characters | Type | Comment | 69 +===================+===============+================================+ 70 | :attr:`%%` | *n/a* | The literal % character. | 71 +-------------------+---------------+--------------------------------+ 72 | :attr:`%c` | int | A single byte, | 73 | | | represented as a C int. | 74 +-------------------+---------------+--------------------------------+ 75 | :attr:`%d` | int | Equivalent to | 76 | | | ``printf("%d")``. [1]_ | 77 +-------------------+---------------+--------------------------------+ 78 | :attr:`%u` | unsigned int | Equivalent to | 79 | | | ``printf("%u")``. [1]_ | 80 +-------------------+---------------+--------------------------------+ 81 | :attr:`%ld` | long | Equivalent to | 82 | | | ``printf("%ld")``. [1]_ | 83 +-------------------+---------------+--------------------------------+ 84 | :attr:`%lu` | unsigned long | Equivalent to | 85 | | | ``printf("%lu")``. [1]_ | 86 +-------------------+---------------+--------------------------------+ 87 | :attr:`%zd` | Py_ssize_t | Equivalent to | 88 | | | ``printf("%zd")``. [1]_ | 89 +-------------------+---------------+--------------------------------+ 90 | :attr:`%zu` | size_t | Equivalent to | 91 | | | ``printf("%zu")``. [1]_ | 92 +-------------------+---------------+--------------------------------+ 93 | :attr:`%i` | int | Equivalent to | 94 | | | ``printf("%i")``. [1]_ | 95 +-------------------+---------------+--------------------------------+ 96 | :attr:`%x` | int | Equivalent to | 97 | | | ``printf("%x")``. [1]_ | 98 +-------------------+---------------+--------------------------------+ 99 | :attr:`%s` | const char\* | A null-terminated C character | 100 | | | array. | 101 +-------------------+---------------+--------------------------------+ 102 | :attr:`%p` | const void\* | The hex representation of a C | 103 | | | pointer. Mostly equivalent to | 104 | | | ``printf("%p")`` except that | 105 | | | it is guaranteed to start with | 106 | | | the literal ``0x`` regardless | 107 | | | of what the platform's | 108 | | | ``printf`` yields. | 109 +-------------------+---------------+--------------------------------+ 110 111 An unrecognized format character causes all the rest of the format string to be 112 copied as-is to the result object, and any extra arguments discarded. 113 114 .. [1] For integer specifiers (d, u, ld, lu, zd, zu, i, x): the 0-conversion 115 flag has effect even when a precision is given. 116 117 118 .. c:function:: PyObject* PyBytes_FromFormatV(const char *format, va_list vargs) 119 120 Identical to :c:func:`PyBytes_FromFormat` except that it takes exactly two 121 arguments. 122 123 124 .. c:function:: PyObject* PyBytes_FromObject(PyObject *o) 125 126 Return the bytes representation of object *o* that implements the buffer 127 protocol. 128 129 130 .. c:function:: Py_ssize_t PyBytes_Size(PyObject *o) 131 132 Return the length of the bytes in bytes object *o*. 133 134 135 .. c:function:: Py_ssize_t PyBytes_GET_SIZE(PyObject *o) 136 137 Macro form of :c:func:`PyBytes_Size` but without error checking. 138 139 140 .. c:function:: char* PyBytes_AsString(PyObject *o) 141 142 Return a pointer to the contents of *o*. The pointer 143 refers to the internal buffer of *o*, which consists of ``len(o) + 1`` 144 bytes. The last byte in the buffer is always null, regardless of 145 whether there are any other null bytes. The data must not be 146 modified in any way, unless the object was just created using 147 ``PyBytes_FromStringAndSize(NULL, size)``. It must not be deallocated. If 148 *o* is not a bytes object at all, :c:func:`PyBytes_AsString` returns *NULL* 149 and raises :exc:`TypeError`. 150 151 152 .. c:function:: char* PyBytes_AS_STRING(PyObject *string) 153 154 Macro form of :c:func:`PyBytes_AsString` but without error checking. 155 156 157 .. c:function:: int PyBytes_AsStringAndSize(PyObject *obj, char **buffer, Py_ssize_t *length) 158 159 Return the null-terminated contents of the object *obj* 160 through the output variables *buffer* and *length*. 161 162 If *length* is *NULL*, the bytes object 163 may not contain embedded null bytes; 164 if it does, the function returns ``-1`` and a :exc:`ValueError` is raised. 165 166 The buffer refers to an internal buffer of *obj*, which includes an 167 additional null byte at the end (not counted in *length*). The data 168 must not be modified in any way, unless the object was just created using 169 ``PyBytes_FromStringAndSize(NULL, size)``. It must not be deallocated. If 170 *obj* is not a bytes object at all, :c:func:`PyBytes_AsStringAndSize` 171 returns ``-1`` and raises :exc:`TypeError`. 172 173 .. versionchanged:: 3.5 174 Previously, :exc:`TypeError` was raised when embedded null bytes were 175 encountered in the bytes object. 176 177 178 .. c:function:: void PyBytes_Concat(PyObject **bytes, PyObject *newpart) 179 180 Create a new bytes object in *\*bytes* containing the contents of *newpart* 181 appended to *bytes*; the caller will own the new reference. The reference to 182 the old value of *bytes* will be stolen. If the new object cannot be 183 created, the old reference to *bytes* will still be discarded and the value 184 of *\*bytes* will be set to *NULL*; the appropriate exception will be set. 185 186 187 .. c:function:: void PyBytes_ConcatAndDel(PyObject **bytes, PyObject *newpart) 188 189 Create a new bytes object in *\*bytes* containing the contents of *newpart* 190 appended to *bytes*. This version decrements the reference count of 191 *newpart*. 192 193 194 .. c:function:: int _PyBytes_Resize(PyObject **bytes, Py_ssize_t newsize) 195 196 A way to resize a bytes object even though it is "immutable". Only use this 197 to build up a brand new bytes object; don't use this if the bytes may already 198 be known in other parts of the code. It is an error to call this function if 199 the refcount on the input bytes object is not one. Pass the address of an 200 existing bytes object as an lvalue (it may be written into), and the new size 201 desired. On success, *\*bytes* holds the resized bytes object and ``0`` is 202 returned; the address in *\*bytes* may differ from its input value. If the 203 reallocation fails, the original bytes object at *\*bytes* is deallocated, 204 *\*bytes* is set to *NULL*, :exc:`MemoryError` is set, and ``-1`` is 205 returned. 206
