Lec 6, Wed 01/22

Thursday Lecture 06 Notes

Announcements:

• Pay attention to minor details! They matter a lot.
• The review is tomorrow (Fri, Jan 24) at 1:30pm in HFH 1132. If any details about the time or location change, we will post on Piazza.
• We will post a link to the notes and slides from the review session on Piazza.
• Bring a pencil and eraser to the exam. No bluebook/scantron.

Review

Questions:

• Q: If we want to extract a certain part of a string using negative indexing, what kind of format should we use?
  • A: A similar way, using the same logic. Just remember that the last number in the index is NOT included.

    alpha = "abcdefghi"
    >>> alpha[-9:-7]
    "ab"
    

    As a shortcut if you don’t want to count the characters, use the length of the string provided by the len function!

    alpha = "abcdefghi"
    >>> alpha[-len(alpha):-7]
    "ab"
    

• Q: Does capitalization matter when you compare strings?
  • A: Yes! 'y' is not the same as 'Y'
• Q: Do you use the return in the hello() function because of the if/else conditional??
  • A: No. return vs print has nothing to do with the conditional of the function. We used return because the instructions specified to return rather than just print.

Using Conditionals

Example:

raining = input("is it raining? [y/n] ")

if (raining == 'y')
    print("It is raining")
    
elif (raining == 'n'):
    print('it is not raining')

else:
    print("not an option")
    

if you wanted to be able to use other inputs (e.g., 'y' 'yes' 'Y') to be able to output “It is raining”, you would do so by changing the comparison in the conditional like this:

if (raining == 'y' or raining == 'Y' or raining == 'yes'):
    print("It is raining")
    

Q: could we get around this by putting all possible conditionals in a list or something and then use an in statement??? A: Yes!

if raining in ('y','Y','yes'):
    print("It is raining")
    

Q:

We posted a follow-up about it on Piazza: https://piazza.com/class/k54kv5vmxdu67o?cid=41.