Programming Languages Transcript of Lecture of 13th October at 9:15

(* Demonstrates the list functions again from previous lecture *)
>>> a = [0,1,2,3]
>>> a[0]
0
>>> a[1]
1
>>> a{1:1]
[]
>>> a[0]=4
>>> a
[4,1,2,3]

(* How to reverse a list *)
>>> a.reverse()
>>> a
[3,2,1,4]

(* Adding 5 to the end of the list *)
>>> a.append(5)
>>> a
[3,2,1,4,5]

(* Remove and return the last item in the list *)
>>> a.pop()
5

(* Create a new pointer to the same list *)
>>> b = a
>>> b.pop()
4
>>> b
[3,2,1]
>>> a
[3,2,1]

(* Create a pointer to a new copy of the list a *)
>>> b = list(a)
>>> b
[3,2,1]
>>> a
[3,2,1]

>>> b.pop()
1
>>> b
[3,2]
>>> a
[3,2,1]

(* How do a and b compare if they are both pointers to the same list? *)
>>> a = [1,2,3]
>>> b = a
>>> b is a
True
>>> b == a
True

(* How do a and b compare if b points to a copy of a? *)
>>> b = list(a)
>>> b is a
False
>>> b==a
True

(* BONUS: Trying both comparison methods at the same time on a list and its copy *)
>>> (b is a, b == a)
(False, True)