[Tutor] What is wrong my code?

[Hoffmann]

--- Danny Yoo <dyoo at hkn.eecs.berkeley.edu> wrote:

> > #!/usr/bin/python
> >
> > import math
> >
> > print '''This program calculates the lenght of the
> > hypotenuse of a right triangle
> >     given the lenghts of the two legs as
> > parameters.\n'''
> >
> > leg1 = input('Enter the first leg of the triangle:
> ')
> > leg2 = input('Enter the second leg of the
> triangle: ')
> 
> 
> Hi Hoffmann,
> 
> Although this works, the use of input() is a little
> less safe than using
> raw_input(), and input gives slightly unhappy error
> messages on certain
> kinds of input.  For example:
> 
> ######
> >>> input("number? ")
> number? four
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "<string>", line 1, in <module>
> NameError: name 'four' is not defined
> ######
> 
> That is, certain kinds of input will give us things
> like NameError.
> 
> 
> But here's another example where input() can do
> funny things:
> 
> ######
> >>> def test():
> ...     x = input("x?: ")
> ...     y = input("y?: ")
> ...     print x, y
> ...
> >>> test()
> x?: 3
> y?: x
> 3 3
> ######
> 
> Although this is "cute", it shows that it's also
> terribly hard to figure
> out what's going on with input() sometimes.  *grin*
> 
> So because of this, I'd recommend using raw_input()
> instead: even though
> you have to do a little more work to get numbers out
> of it, it's
> ultimately a bit saner and more reliable to use than
> input().
> 
> 
> 
> > def hypotenuse(x, y):
> >     result = math.sqrt(x**2 + y**2)
> >     return result
> 
> There's no need to do the assignment to 'result'
> here.  We can return the
> value straightaway:
> 
> #################################
> def hypotenuse(x, y):
>     return math.sqrt(x**2 + y**2)
> #################################
> 
> 
> 
> Although it's "obvious", it might also help to add
> some kind of
> documentation string explaining hypotenuse, and what
> it takes in
> and returns.  Something like:
> 
>
###################################################################
> def hypotenuse(x, y):
>     """hypotenuse: number number -> number
>     hypotenuse() returns the length of the
> hypotenuse of a right
>     triangle with legs of length x and y."""
>     # ... rest of function body
>
###################################################################
> 
> might seem like overkill for such a simple function,
> but the habit is a
> good one.
> 
> 
> In an ideal world, all functions would have some
> kind of comment like
> that, to communicate the human intent to the reader.
>  I admit that I often
> just hack functions up without saying what they
> mean... but I do feel
> guilty afterwards.  *grin*
> 
> 
> I hope this helps!
> 
Hi Danny,

I did like your comments about input and raw_input.
What about if I use on my program:

leg1 = int( raw_input('Enter the first leg of the
triangle: ') ) 
leg2= int( raw_input('Enter the second leg of the
triangle: ') )  

What do you think? This is better/safer, right?

Thanks,
Hoffmann


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