Wk 2: Background in Python and Unix

Question 1

Python tool for debugging online

Answer 1

pythontutor.com

Question 2

What is dynamic typing of variables?

Answer 2

you don’t have to declare type of variable

Question 3

Why does python allow for dynamic typing?

Answer 3

Everything in python is an object

Question 4

What happens when you assign a different type to a variable that’s already been created?

Answer 4

Python creates a new object, and then points your variable at the new one (garbage collector takes care of original)

Question 5

IS operator

Answer 5

tests if two variables point to the same object

Question 6

assign a value to a variable

Answer 6

X = 5, X = “hello”, X = 4.5

Question 7

Some string methods in python

Answer 7

capitalize(), lower() – return copies of the original (but don’t modify the original)

Question 8

How to call lower() method on variable x?

Answer 8

x.lower()

Question 9

How to assign output of x.lower to x?

Answer 9

x = x.lower()

Question 10

Loop syntax example in python

Answer 10

for i in range (0,10): print (i)

Question 11

Range(x,y) - x is inclusive? y is inclusive?

Answer 11

x is inclusive, y is exclusive

Question 12

loop syntax increment by 2

Answer 12

for i in range (0,10,2): print (i)

Question 13

while loop equivalent of “for i in range (0,10,2)”

Answer 13

i = 0; while i < 12: print(i); i+=3

Question 14

Print var1 if var1 == 2

Answer 14

if var1 == 2:

print(var1)

Question 15

If / else if / else syntax

Answer 15

if x==2; elif x==3: else:

Question 16

define a function

Answer 16

def func_name(args): xxxx; return val

Question 17

what’s the downside of not having to define the type of the args or the return value

Answer 17

will get the error at run time if a value is passed that isn’t the expected type

Question 18

what does a function return if there is not return statement

Answer 18

returns None

Question 19

What’s the scope of a variable set at the top of the code

Answer 19

Global - it’s available throughout all code, and the functions

Question 20

What’s the scope of a variable set inside of a function

Answer 20

only available in that function, unless it has the same name as a prev set global var