9.2 Controlling the flow inside the loop

Sometimes it is necessary to jump out of the loop or to go directly to the next loop iteration. These two operations are performed by the commands break and continue.  

The keyword break is used to terminate the loop before it is completely executed—it breaks the loop.

Two situations can occur in loops with a break statement:

• The loop is completely executed.

• The loop is left when reaching break before it was completely executed.

For the first case, special actions can be defined in an else block, which is executed if the whole list is traversed. This is useful in general if the purpose of the for loop is to find something and stop. Examples might be searching for one element satisfying a certain property inside a list. If such an element is not found, the else block is executed.

Here is a common usage in scientific computing: Quite...