On 19/01/14 13:59, rahmad akbar wrote:
hey guys, super noob here, i am trying to understand the following code
from google tutorial which i failed to comprehend
Others have answered the specifics but some general advice here:
1) never forget the Python >>> prompt.
Try things out if you don't understand them.
Look at the results. Its a great learning tool.
2) use the built in help() function at the >>> prompt
Those two aids will answer about 80% of your questions.
And for the rest there is the tutor list! :-)
def not_bad(s):
n = s.find('not')
b = s.find('bad')
if n != -1 and b != -1 and b > n:
s = s[:n] + 'good' + s[b+3:]
return s
on the following lines, what is -1, is that index number?
>>> help(''.find)
Help on built-in function find:
find(...)
S.find(sub[, start[, end]]) -> int
Return the lowest index in S where substring sub is found,
such that sub is contained within S[start:end]. Optional
arguments start and end are interpreted as in slice notation.
Return -1 on failure.
(END)
>>> s = "Test string thats not interesting but not bad either"
>>> s.find('not')
18
>>> s.find('bad')
42
>>> s.find('gobbledegook')
-1
understand the entire second line
if n != -1 and b != -1 and b > n:
s = s[:n] + 'good' + s[b+3:]
Again try this in bits at the >>> prompt:
>>> s[:18] # using the value found above
'Test string thats '
>>> s[42+3:] # again using value above
' either'
>>> s[:18] + 'good' + s[45:]
'Test string thats good either'
Hopefully that gives you some ideas on how
to use the >>> prompt to answer questions
as they arise.
--
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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