1 .. highlightlang:: c 2 3 .. _stringobjects: 4 5 String/Bytes Objects 6 -------------------- 7 8 These functions raise :exc:`TypeError` when expecting a string parameter and are 9 called with a non-string parameter. 10 11 .. note:: 12 13 These functions have been renamed to PyBytes_* in Python 3.x. Unless 14 otherwise noted, the PyBytes functions available in 3.x are aliased to their 15 PyString_* equivalents to help porting. 16 17 .. index:: object: string 18 19 20 .. c:type:: PyStringObject 21 22 This subtype of :c:type:`PyObject` represents a Python string object. 23 24 25 .. c:var:: PyTypeObject PyString_Type 26 27 .. index:: single: StringType (in module types) 28 29 This instance of :c:type:`PyTypeObject` represents the Python string type; it is 30 the same object as ``str`` and ``types.StringType`` in the Python layer. . 31 32 33 .. c:function:: int PyString_Check(PyObject *o) 34 35 Return true if the object *o* is a string object or an instance of a subtype of 36 the string type. 37 38 .. versionchanged:: 2.2 39 Allowed subtypes to be accepted. 40 41 42 .. c:function:: int PyString_CheckExact(PyObject *o) 43 44 Return true if the object *o* is a string object, but not an instance of a 45 subtype of the string type. 46 47 .. versionadded:: 2.2 48 49 50 .. c:function:: PyObject* PyString_FromString(const char *v) 51 52 Return a new string object with a copy of the string *v* as value on success, 53 and *NULL* on failure. The parameter *v* must not be *NULL*; it will not be 54 checked. 55 56 57 .. c:function:: PyObject* PyString_FromStringAndSize(const char *v, Py_ssize_t len) 58 59 Return a new string object with a copy of the string *v* as value and length 60 *len* on success, and *NULL* on failure. If *v* is *NULL*, the contents of the 61 string are uninitialized. 62 63 .. versionchanged:: 2.5 64 This function used an :c:type:`int` type for *len*. This might require 65 changes in your code for properly supporting 64-bit systems. 66 67 68 .. c:function:: PyObject* PyString_FromFormat(const char *format, ...) 69 70 Take a C :c:func:`printf`\ -style *format* string and a variable number of 71 arguments, calculate the size of the resulting Python string and return a string 72 with the values formatted into it. The variable arguments must be C types and 73 must correspond exactly to the format characters in the *format* string. The 74 following format characters are allowed: 75 76 .. % This should be exactly the same as the table in PyErr_Format. 77 .. % One should just refer to the other. 78 .. % The descriptions for %zd and %zu are wrong, but the truth is complicated 79 .. % because not all compilers support the %z width modifier -- we fake it 80 .. % when necessary via interpolating PY_FORMAT_SIZE_T. 81 .. % Similar comments apply to the %ll width modifier and 82 .. % PY_FORMAT_LONG_LONG. 83 .. % %u, %lu, %zu should have "new in Python 2.5" blurbs. 84 85 +-------------------+---------------+--------------------------------+ 86 | Format Characters | Type | Comment | 87 +===================+===============+================================+ 88 | :attr:`%%` | *n/a* | The literal % character. | 89 +-------------------+---------------+--------------------------------+ 90 | :attr:`%c` | int | A single character, | 91 | | | represented as a C int. | 92 +-------------------+---------------+--------------------------------+ 93 | :attr:`%d` | int | Exactly equivalent to | 94 | | | ``printf("%d")``. | 95 +-------------------+---------------+--------------------------------+ 96 | :attr:`%u` | unsigned int | Exactly equivalent to | 97 | | | ``printf("%u")``. | 98 +-------------------+---------------+--------------------------------+ 99 | :attr:`%ld` | long | Exactly equivalent to | 100 | | | ``printf("%ld")``. | 101 +-------------------+---------------+--------------------------------+ 102 | :attr:`%lu` | unsigned long | Exactly equivalent to | 103 | | | ``printf("%lu")``. | 104 +-------------------+---------------+--------------------------------+ 105 | :attr:`%lld` | long long | Exactly equivalent to | 106 | | | ``printf("%lld")``. | 107 +-------------------+---------------+--------------------------------+ 108 | :attr:`%llu` | unsigned | Exactly equivalent to | 109 | | long long | ``printf("%llu")``. | 110 +-------------------+---------------+--------------------------------+ 111 | :attr:`%zd` | Py_ssize_t | Exactly equivalent to | 112 | | | ``printf("%zd")``. | 113 +-------------------+---------------+--------------------------------+ 114 | :attr:`%zu` | size_t | Exactly equivalent to | 115 | | | ``printf("%zu")``. | 116 +-------------------+---------------+--------------------------------+ 117 | :attr:`%i` | int | Exactly equivalent to | 118 | | | ``printf("%i")``. | 119 +-------------------+---------------+--------------------------------+ 120 | :attr:`%x` | int | Exactly equivalent to | 121 | | | ``printf("%x")``. | 122 +-------------------+---------------+--------------------------------+ 123 | :attr:`%s` | char\* | A null-terminated C character | 124 | | | array. | 125 +-------------------+---------------+--------------------------------+ 126 | :attr:`%p` | void\* | The hex representation of a C | 127 | | | pointer. Mostly equivalent to | 128 | | | ``printf("%p")`` except that | 129 | | | it is guaranteed to start with | 130 | | | the literal ``0x`` regardless | 131 | | | of what the platform's | 132 | | | ``printf`` yields. | 133 +-------------------+---------------+--------------------------------+ 134 135 An unrecognized format character causes all the rest of the format string to be 136 copied as-is to the result string, and any extra arguments discarded. 137 138 .. note:: 139 140 The `"%lld"` and `"%llu"` format specifiers are only available 141 when :const:`HAVE_LONG_LONG` is defined. 142 143 .. versionchanged:: 2.7 144 Support for `"%lld"` and `"%llu"` added. 145 146 147 .. c:function:: PyObject* PyString_FromFormatV(const char *format, va_list vargs) 148 149 Identical to :c:func:`PyString_FromFormat` except that it takes exactly two 150 arguments. 151 152 153 .. c:function:: Py_ssize_t PyString_Size(PyObject *string) 154 155 Return the length of the string in string object *string*. 156 157 .. versionchanged:: 2.5 158 This function returned an :c:type:`int` type. This might require changes 159 in your code for properly supporting 64-bit systems. 160 161 162 .. c:function:: Py_ssize_t PyString_GET_SIZE(PyObject *string) 163 164 Macro form of :c:func:`PyString_Size` but without error checking. 165 166 .. versionchanged:: 2.5 167 This macro returned an :c:type:`int` type. This might require changes in 168 your code for properly supporting 64-bit systems. 169 170 171 .. c:function:: char* PyString_AsString(PyObject *string) 172 173 Return a NUL-terminated representation of the contents of *string*. The pointer 174 refers to the internal buffer of *string*, not a copy. The data must not be 175 modified in any way, unless the string was just created using 176 ``PyString_FromStringAndSize(NULL, size)``. It must not be deallocated. If 177 *string* is a Unicode object, this function computes the default encoding of 178 *string* and operates on that. If *string* is not a string object at all, 179 :c:func:`PyString_AsString` returns *NULL* and raises :exc:`TypeError`. 180 181 182 .. c:function:: char* PyString_AS_STRING(PyObject *string) 183 184 Macro form of :c:func:`PyString_AsString` but without error checking. Only 185 string objects are supported; no Unicode objects should be passed. 186 187 188 .. c:function:: int PyString_AsStringAndSize(PyObject *obj, char **buffer, Py_ssize_t *length) 189 190 Return a NUL-terminated representation of the contents of the object *obj* 191 through the output variables *buffer* and *length*. 192 193 The function accepts both string and Unicode objects as input. For Unicode 194 objects it returns the default encoded version of the object. If *length* is 195 *NULL*, the resulting buffer may not contain NUL characters; if it does, the 196 function returns ``-1`` and a :exc:`TypeError` is raised. 197 198 The buffer refers to an internal string buffer of *obj*, not a copy. The data 199 must not be modified in any way, unless the string was just created using 200 ``PyString_FromStringAndSize(NULL, size)``. It must not be deallocated. If 201 *string* is a Unicode object, this function computes the default encoding of 202 *string* and operates on that. If *string* is not a string object at all, 203 :c:func:`PyString_AsStringAndSize` returns ``-1`` and raises :exc:`TypeError`. 204 205 .. versionchanged:: 2.5 206 This function used an :c:type:`int *` type for *length*. This might 207 require changes in your code for properly supporting 64-bit systems. 208 209 210 .. c:function:: void PyString_Concat(PyObject **string, PyObject *newpart) 211 212 Create a new string object in *\*string* containing the contents of *newpart* 213 appended to *string*; the caller will own the new reference. The reference to 214 the old value of *string* will be stolen. If the new string cannot be created, 215 the old reference to *string* will still be discarded and the value of 216 *\*string* will be set to *NULL*; the appropriate exception will be set. 217 218 219 .. c:function:: void PyString_ConcatAndDel(PyObject **string, PyObject *newpart) 220 221 Create a new string object in *\*string* containing the contents of *newpart* 222 appended to *string*. This version decrements the reference count of *newpart*. 223 224 225 .. c:function:: int _PyString_Resize(PyObject **string, Py_ssize_t newsize) 226 227 A way to resize a string object even though it is "immutable". Only use this to 228 build up a brand new string object; don't use this if the string may already be 229 known in other parts of the code. It is an error to call this function if the 230 refcount on the input string object is not one. Pass the address of an existing 231 string object as an lvalue (it may be written into), and the new size desired. 232 On success, *\*string* holds the resized string object and ``0`` is returned; 233 the address in *\*string* may differ from its input value. If the reallocation 234 fails, the original string object at *\*string* is deallocated, *\*string* is 235 set to *NULL*, a memory exception is set, and ``-1`` is returned. 236 237 .. versionchanged:: 2.5 238 This function used an :c:type:`int` type for *newsize*. This might 239 require changes in your code for properly supporting 64-bit systems. 240 241 .. c:function:: PyObject* PyString_Format(PyObject *format, PyObject *args) 242 243 Return a new string object from *format* and *args*. Analogous to ``format % 244 args``. The *args* argument must be a tuple or dict. 245 246 247 .. c:function:: void PyString_InternInPlace(PyObject **string) 248 249 Intern the argument *\*string* in place. The argument must be the address of a 250 pointer variable pointing to a Python string object. If there is an existing 251 interned string that is the same as *\*string*, it sets *\*string* to it 252 (decrementing the reference count of the old string object and incrementing the 253 reference count of the interned string object), otherwise it leaves *\*string* 254 alone and interns it (incrementing its reference count). (Clarification: even 255 though there is a lot of talk about reference counts, think of this function as 256 reference-count-neutral; you own the object after the call if and only if you 257 owned it before the call.) 258 259 .. note:: 260 261 This function is not available in 3.x and does not have a PyBytes alias. 262 263 264 .. c:function:: PyObject* PyString_InternFromString(const char *v) 265 266 A combination of :c:func:`PyString_FromString` and 267 :c:func:`PyString_InternInPlace`, returning either a new string object that has 268 been interned, or a new ("owned") reference to an earlier interned string object 269 with the same value. 270 271 .. note:: 272 273 This function is not available in 3.x and does not have a PyBytes alias. 274 275 276 .. c:function:: PyObject* PyString_Decode(const char *s, Py_ssize_t size, const char *encoding, const char *errors) 277 278 Create an object by decoding *size* bytes of the encoded buffer *s* using the 279 codec registered for *encoding*. *encoding* and *errors* have the same meaning 280 as the parameters of the same name in the :func:`unicode` built-in function. 281 The codec to be used is looked up using the Python codec registry. Return 282 *NULL* if an exception was raised by the codec. 283 284 .. note:: 285 286 This function is not available in 3.x and does not have a PyBytes alias. 287 288 .. versionchanged:: 2.5 289 This function used an :c:type:`int` type for *size*. This might require 290 changes in your code for properly supporting 64-bit systems. 291 292 293 .. c:function:: PyObject* PyString_AsDecodedObject(PyObject *str, const char *encoding, const char *errors) 294 295 Decode a string object by passing it to the codec registered for *encoding* and 296 return the result as Python object. *encoding* and *errors* have the same 297 meaning as the parameters of the same name in the string :meth:`encode` method. 298 The codec to be used is looked up using the Python codec registry. Return *NULL* 299 if an exception was raised by the codec. 300 301 .. note:: 302 303 This function is not available in 3.x and does not have a PyBytes alias. 304 305 306 .. c:function:: PyObject* PyString_Encode(const char *s, Py_ssize_t size, const char *encoding, const char *errors) 307 308 Encode the :c:type:`char` buffer of the given size by passing it to the codec 309 registered for *encoding* and return a Python object. *encoding* and *errors* 310 have the same meaning as the parameters of the same name in the string 311 :meth:`encode` method. The codec to be used is looked up using the Python codec 312 registry. Return *NULL* if an exception was raised by the codec. 313 314 .. note:: 315 316 This function is not available in 3.x and does not have a PyBytes alias. 317 318 .. versionchanged:: 2.5 319 This function used an :c:type:`int` type for *size*. This might require 320 changes in your code for properly supporting 64-bit systems. 321 322 323 .. c:function:: PyObject* PyString_AsEncodedObject(PyObject *str, const char *encoding, const char *errors) 324 325 Encode a string object using the codec registered for *encoding* and return the 326 result as Python object. *encoding* and *errors* have the same meaning as the 327 parameters of the same name in the string :meth:`encode` method. The codec to be 328 used is looked up using the Python codec registry. Return *NULL* if an exception 329 was raised by the codec. 330 331 .. note:: 332 333 This function is not available in 3.x and does not have a PyBytes alias. 334
