Python/docs/3.8/c-api/list

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 non-negative; indexing from the end of the list is not supported. If index is out of bounds (<0 or >=len(list)), 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. If index is out of bounds, return -1 and set an IndexError exception.

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]. Indexing from the end of the list is 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. Indexing from the end of the list is 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.