.. index:: py::builtins::list::index

.. _doxycast_pypp_classpy_1_1builtins_1_1list_1a15eece8d1b9d1122d921a2af783b4d15:

.. _py-builtins-list-index:

*py::builtins::list::*\ index
=============================

.. code-block:: cpp

     std::size_t index(const_reference element) const;

Returns the index of given element.

``py::builtins::list::index`` returns the index of given element.
It first checks if there is any ``element`` with the same address
as the address of given element, and return the index of that
element if found, otherwise ``element`` compared by value with
elements in the list.

.. note::

     When comparing by value, if the list contains more than one
     element with given value, index of the first one is
     returned.


Parameter
---------

``element``: The element of look for.


Return value
------------

The index of given element.


Exceptions
----------

:ref:`py-builtins-ValueError` if the element can't be found.


Complexity
----------

Linear in the position of ``element`` in the list if there is any
element with the same address as the address of given
``element``, linear in the size of the list plus linear in the
position of ``element`` otherwise.


Example
-------

.. code-block:: cpp

     #include <pypp/builtins/list.hpp>
     #include <pypp/builtins/print.hpp>

     int main()
     {
         py::list<int> nums = {0, 2, 1, 4, 0, 3, 2};

         py::print(nums.index(0)); // Argument is temporary reference, value 0
         py::print(nums.index(nums[6])); // Argument is reference to element, value 2
     }

**Output**:

.. code-block:: text

     0
     6