python_doc_md/Advanced/c-api/list.md

List Objects {#listobjects}

::: index pair: object; list :::

This subtype of PyObject{.interpreted-text role="c:type"} represents a Python list object.

This instance of PyTypeObject{.interpreted-text role="c:type"} represents the Python list type. This is the same object as list{.interpreted-text role="class"} in the Python layer.

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

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

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

:::: note ::: title 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{.interpreted-text role="c:func"} or expose the object to Python code before setting all items to a real object with PyList_SetItem{.interpreted-text role="c:func"} or PyList_SET_ITEM(){.interpreted-text role="c:func"}. The following APIs are safe APIs before the list is fully initialized: PyList_SetItem(){.interpreted-text role="c:func"} and PyList_SET_ITEM(){.interpreted-text role="c:func"}. ::::

::: index pair: built-in function; len :::

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

Similar to PyList_Size{.interpreted-text role="c:func"}, but without error checking.

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{.interpreted-text role="exc"} exception.

::: versionadded 3.13 :::

Like PyList_GetItemRef{.interpreted-text role="c:func"}, but returns a borrowed reference{.interpreted-text role="term"} instead of a strong reference{.interpreted-text role="term"}.

Similar to PyList_GetItem{.interpreted-text role="c:func"}, but without error checking.

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{.interpreted-text role="exc"} exception.

:::: note ::: title Note :::

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

Macro form of PyList_SetItem{.interpreted-text role="c:func"} without error checking. This is normally only used to fill in new lists where there is no previous content.

Bounds checking is performed as an assertion if Python is built in debug mode <debug-build>{.interpreted-text role="ref"} or with assertions <--with-assertions>{.interpreted-text role="option"}.

:::: note ::: title Note :::

This macro "steals" a reference to item, and, unlike PyList_SetItem{.interpreted-text role="c:func"}, does not discard a reference to any item that is being replaced; any reference in list at position i will be leaked. ::::

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).

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).

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.

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.

Extend list with the contents of iterable. This is the same as PyList_SetSlice(list, PY_SSIZE_T_MAX, PY_SSIZE_T_MAX, iterable) and analogous to list.extend(iterable) or list += iterable.

Raise an exception and return -1 if list is not a list{.interpreted-text role="class"} object. Return 0 on success.

::: versionadded 3.13 :::

Remove all items from list. This is the same as PyList_SetSlice(list, 0, PY_SSIZE_T_MAX, NULL) and analogous to list.clear() or del list[:].

Raise an exception and return -1 if list is not a list{.interpreted-text role="class"} object. Return 0 on success.

::: versionadded 3.13 :::

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

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

::: index pair: built-in function; tuple :::

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