List Objects — Python 3.6.6 documentation

# List Objects

`PyListObject`

  This subtype of `PyObject` represents a Python list object.

PyTypeObject `PyList_Type`

  This instance of `PyTypeObject` represents the Python list type. This is the same object as `list` in the Python layer.

int `PyList_Check`(PyObject *p)

  Return true if p is a list object or an instance of a subtype of the list type.

int `PyList_CheckExact`(PyObject *p)

  Return true if p is a list object, but not an instance of a subtype of the list type.

PyObject* `PyList_New`(Py_ssize_t len)
  Return value: New reference.

  Return a new list of length len on success, or NULL on failure.

  Note

  If len is greater than zero, the returned list object’s items are set to `NULL`. Thus you cannot use abstract API functions such as `PySequence_SetItem()` or expose the object to Python code before setting all items to a real object with `PyList_SetItem()`.

Py_ssize_t `PyList_Size`(PyObject *list)

  Return the length of the list object in list; this is equivalent to `len(list)` on a list object.

Py_ssize_t `PyList_GET_SIZE`(PyObject *list)

  Macro form of `PyList_Size()` without error checking.

PyObject* `PyList_GetItem`(PyObject *list, Py_ssize_t index)
  Return value: Borrowed reference.

  Return the object at position index in the list pointed to by list. The position must be positive, indexing from the end of the list is not supported. If index is out of bounds, return NULL and set an `IndexError` exception.

PyObject* `PyList_GET_ITEM`(PyObject *list, Py_ssize_t i)
  Return value: Borrowed reference.

  Macro form of `PyList_GetItem()` without error checking.

int `PyList_SetItem`(PyObject *list, Py_ssize_t index, PyObject *item)

  Set the item at index index in list to item. Return `0` on success or `-1` on failure.

  Note

  This function “steals” a reference to item and discards a reference to an item already in the list at the affected position.

void `PyList_SET_ITEM`(PyObject *list, Py_ssize_t i, PyObject *o)

  Macro form of `PyList_SetItem()` without error checking. This is normally only used to fill in new lists where there is no previous content.

  Note

  This macro “steals” a reference to item, and, unlike `PyList_SetItem()`, does not discard a reference to any item that is being replaced; any reference in list at position i will be leaked.

int `PyList_Insert`(PyObject *list, Py_ssize_t index, PyObject *item)

  Insert the item item into list list in front of index index. Return `0` if successful; return `-1` and set an exception if unsuccessful. Analogous to `list.insert(index, item)`.

int `PyList_Append`(PyObject *list, PyObject *item)

  Append the object item at the end of list list. Return `0` if successful; return `-1` and set an exception if unsuccessful. Analogous to `list.append(item)`.

PyObject* `PyList_GetSlice`(PyObject *list, Py_ssize_t low, Py_ssize_t high)
  Return value: New reference.

  Return a list of the objects in list containing the objects between low and high. Return NULL and set an exception if unsuccessful. Analogous to `list[low:high]`. Negative indices, as when slicing from Python, are not supported.

int `PyList_SetSlice`(PyObject *list, Py_ssize_t low, Py_ssize_t high, PyObject *itemlist)

  Set the slice of list between low and high to the contents of itemlist. Analogous to `list[low:high] = itemlist`. The itemlist may be NULL, indicating the assignment of an empty list (slice deletion). Return `0` on success, `-1` on failure. Negative indices, as when slicing from Python, are not supported.

int `PyList_Sort`(PyObject *list)

  Sort the items of list in place. Return `0` on success, `-1` on failure. This is equivalent to `list.sort()`.

int `PyList_Reverse`(PyObject *list)

  Reverse the items of list in place. Return `0` on success, `-1` on failure. This is the equivalent of `list.reverse()`.

PyObject* `PyList_AsTuple`(PyObject *list)
  Return value: New reference.

  Return a new tuple object containing the contents of list; equivalent to `tuple(list)`.

int `PyList_ClearFreeList`()

  Clear the free list. Return the total number of freed items.

  New in version 3.3.