[Tutor] Step Value

[Steven D'Aprano]

Vincent Balmori wrote:
> Here is my updated code. As simple as this may be, I am a little lost again.
> I appreciate the help and explanations to try to push me to get this on my
> own, but at this point (especially after one week) this is when me being
> given the answer with an explanation will help me much more, so I can
> understand how it works better.
> 
> def ask_number(question, low, high, step = 1):
>     """Ask for a number within a range."""
>     response = None
>     while response not in range(low, high, step):
>         response = int(input(question))
>     return response


You've got it now! Well done.

The trick is, you have to include the argument in the function parameter 
list, AND give it a value. The part "step=1" inside the parentheses of 
the "def" line does exactly that.

def ask_number(question, low, high, step=1):
....................................^^^^^^


Suppose you call the function like this:

ask_number("hello", 1, 10)

Python takes the arguments you give from left to right and assigns them 
to the function parameters:

question = "hello"
low = 1
high = 10
step = ??? no value given

Because you haven't supplied a value for step, Python next looks for a 
default, and finds the value 1, so it uses that instead of raising an 
exception (and error message).



-- 
Steven