Ending a Loop With ``break``
============================

.. index:: ! break

Python, like most programming languages, provides a way to stop a loop before it
would normally finish. The ``break`` keyword immediately stops the execution of
the loop. Program flow then continues with the next line of code below the loop.

.. admonition:: Example

   .. sourcecode:: python
      :linenos:

      for iteration in range(42):
         print('This is iteration number:', iteration+1).

         if iteration > 4:
            break

      print("The loop is done!")

   **Console Output**

   ::

      This is iteration number: 1
      This is iteration number: 2
      This is iteration number: 3
      This is iteration number: 4
      This is iteration number: 5
      This is iteration number: 6
      The loop is done!
   
   #. Line 2 repeats 6 times with values of ``iteration`` from 0 to 5.
   #. The sixth time through the loop, ``iteration`` is 5 and the condition in
      line 4 (``iteration > 4``) evaluates to ``True`` for the first time.
   #. As a result, the program flow reaches the ``break`` statement. The loop
      immediately stops, even though ``range(42)`` would normally keep the loop
      going.
   #. Control moves to the first line of code after the loop.

Why would we need to use ``break``? After all, we tell Python how many times
the loop should repeat in the ``for`` statement.

In some cases, you may want to provide a *second* ending condition. For
example, let's say you need to search through 100,000 items, and you find the
one you want after 5 iterations. In this case, there is no need to wait for the
loop to finish on its own. Adding a ``break`` statement will speed up your
program, especially if you need to use that large range multiple times.

The ``break`` statement can also be used within a ``while`` loop. 

.. index:: ! continue

.. admonition:: Note

   There is another command that interrupts a single iteration of a loop but
   does not end the loop completely. This is the ``continue`` statement.
   
   However, ``continue`` is rarely used, and we will not discuss it in detail
   here. If you are curious, you can find more information at
   `Tutorials Point <https://www.tutorialspoint.com/python/python_loop_control.htm>`__.