On 25/06/14 00:23, keith papa wrote:
1. Hi am new to python and I have a few questions:
Why if you want to write multiple comment you use triple quotation marks
and not the #?
These are technically not the same as comments, they are documentation
strings.
The Python help system will find and display them if you ask it to - it
won't find comments (starting with #).
>>> def f():
... ''' dummy function with doc string'''
... # this is not found
... pass
...
>>> help(f)
displays:
Help on function f in module __main__:
f()
dummy function with doc string
(END)
So the doc string is visible in help but the comment is not.
2. I found this code to be interesting to me because it printed an
output of [1,2,3,4,5,6,7] and not [1,2,3,4:4,5,6,7] why is that?
a= [1,2,3,4,7]
a[4:4] = [5,6]
[4:4] is a slice not an index. It takes a section out of an
existing list. You can see it if you play at the prompt:
>>> a[2:4]
[3,4]
The contents between index 2(inclusive) and 4(exclusive)
Think of it as a knife sitting to the left of the indexed
items cutting out a slice...
>>> a[4:5]
[7]
>>> a[4:4]
[]
In your example you are replacing the empty list found by [4:4] with
[5,6] and that gets inserted back into your original list.
print a
[1,2,3,4,5,6,7]
HTH--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.flickr.com/photos/alangauldphotos
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