1.. highlight:: c 2 3.. _iterator: 4 5Iterator Protocol 6================= 7 8There are two functions specifically for working with iterators. 9 10.. c:function:: int PyIter_Check(PyObject *o) 11 12 Return true if the object *o* supports the iterator protocol. This 13 function always succeeds. 14 15 16.. c:function:: PyObject* PyIter_Next(PyObject *o) 17 18 Return the next value from the iteration *o*. The object must be an iterator 19 (it is up to the caller to check this). If there are no remaining values, 20 returns ``NULL`` with no exception set. If an error occurs while retrieving 21 the item, returns ``NULL`` and passes along the exception. 22 23To write a loop which iterates over an iterator, the C code should look 24something like this:: 25 26 PyObject *iterator = PyObject_GetIter(obj); 27 PyObject *item; 28 29 if (iterator == NULL) { 30 /* propagate error */ 31 } 32 33 while ((item = PyIter_Next(iterator))) { 34 /* do something with item */ 35 ... 36 /* release reference when done */ 37 Py_DECREF(item); 38 } 39 40 Py_DECREF(iterator); 41 42 if (PyErr_Occurred()) { 43 /* propagate error */ 44 } 45 else { 46 /* continue doing useful work */ 47 } 48