Recursive Functions

When a function calls itself, it is known as a Recursive Function. This is like for loops. However, sometimes it allows you to write more elegant and terse functions than can be achieved with a loop.

You can imagine that a function that calls itself might end up in an infinite loop; it is true that you can write a recursive function that will keep running indefinitely:

def print_the_next_number(start):
        print(start + 1)
        return print_the_next_number(start + 1)
print_the_next_number(5)

You should get the following output:

6
7
8
9
10
11

Note

The output mentioned above is truncated.

If you run this code in a Python shell, it will continue printing integers until you interrupt the interpreter (Ctrl + C). Take a look at the preceding code and ensure you understand why it behaves in this manner. The function executes the following steps:

• The function...