Page 39 - Programming the Raspberry Pi Getting Started with Python

Exercise
Try incorporating the preceding test into the dice program. While you are at it, add two more if
statements: one that prints “Good Throw!” if the throw is higher than 10 and one that prints
“Unlucky!” if the throw is less than 4. Try your program out. If you get stuck, you can look at the
solution in the file 3_3_double_dice_solution.py.
Else
In the preceding example, you will see that some of the possible throws can be followed by more than
one message. Any of the if lines could print an extra message if the condition is true. Sometimes you
want a slightly different type of logic, so that if the condition is true, you do one thing and otherwise
you do another. In Python, you use else to accomplish this:

In this case, only one of the two messages will ever be printed.
Another variation on this is elif, which is short for else if. Thus, we could expand the previous
example so that there are three mutually exclusive clauses, like this:

While
Another command for looping is while, which works a little differently than for. The command
while looks a bit like an if command in that it is immediately followed by a condition. In this case,
the condition is for staying in the loop. In other words, the code inside the loop will be executed until
the condition is no longer true. This means that you have to be careful to ensure that the condition will
at some point be false; otherwise, the loop will continue forever and your program will appear to have
hung.
To illustrate the use of while, the dice program has been modified so that it just keeps on rolling

until a double 6 is rolled: