CSSE1001

Question 1

What is the difference between syntax and semantics?

Answer 1

Syntax is what it means for the code to be grammatically correct while semantics is what the code actually does.

For example, the sentence “Colourless green ideas sleep furiously” is correct grammatically (syntax) but doesn’t make sense (semantic)

Question 2

What is Negation and Affirmation?

Answer 2

Negation is when a number is turned into a negative (multiplied by -1) while Affirmation is when a number is turned into a positive (multiplied by +1).

For example, -x is negation while +x is affirmation.

Question 3

Is the following a valid python expression?

>>> 3

Answer 3

Yes, as it is syntactically correct and python is able to read it as opposed to the following

>>> 3-
Syntax error

Question 4

True or false?

If x and y are valid Python expression then x + y and x - y are valid Python expression.

Answer 4

True. Any (syntactically correct) arithmetic expression can be added or subtracted from/to another (syntactically correct) arithmetic expressions

Question 5

What is the highest order of operation?

Answer 5

Parenthesis

Question 6

What comes after parenthesis in the order of operations?

Answer 6

Exponents

Question 7

What operator functions as integer division

Answer 7

//

Question 8

What is integer division

Answer 8

Integer division refers to the process of dividing two integers and obtaining the quotient without any fractional part.

For example, in integer division, 7 ÷ 2 = 3 where 3 is the quotient while there is also a remainder of 1.

Question 9

What operator finds the remainder of an equation?

Question 10

What is a remainder?

Answer 10

If a number cannot be evenly divided by another number, the number left over at the end of the division is called the remainder.

For example, in integer division, 7 ÷ 2 = 3 where 3 is the quotient while there is also a remainder of 1.

Question 11

True or false?

All operations with the same precedence (level of order in operations), are read from left to right.

Answer 11

False. It is true for all except exponentiation with is read from right to left.

Question 12

Using knowledge of order of operations, what will be the output of the following:

>>> 3 * 1 // 2

Answer 12

>>> 3 * 1 // 2
1

The answer is 1

Question 13

What does the following output?

>>> 3//2

Answer 13

>>> 3//2
1

// is integer division. In the expression, 3//2, we basically ask how many 2’s will fit into 3 which is only 1.

Question 14

What does the following output?

>>> 17 // 3

Answer 14

>>> 17 // 3
5

// is integer division. In the expression, 17//3, we basically ask how many 3’s will fit into 17 which is 5.

Question 15

What does the following output?

>>> 2 ** 1 ** 0

Answer 15

>>> 2 ** 1 ** 0
2

In other words, it may be written as

>>> 2 ** (1 ** 0)

Question 16

What does the following output?

>>> 3 * (1 // 2)

Answer 16

>>> 3 * (1 // 2)
0

Question 17

True or false?

Using the divide operator (/) will cause the expression to turn into a float.

Answer 17

True.

As opposed to the following outputting an integer:

>>>3*4
12

The following will output a float

>>> (3*4)/2
 6.0

Question 18

What does the following arithmetic expression evaluate to in Python?

>>> 2 ** 3 % 5 - 1

Answer 18

>>> 2 ** 3 % 5 - 1
2

Question 19

What value gets assigned to x?

>>> x = 35 * 2 % 5 ** 2

Answer 19

>>> x = 35 * 2 % 5 ** 2
>>> x
20

Question 20

What are the three primative control structures?

Answer 20

Sequencing
Conditioning
Looping

Question 21

True or false?

While loops are used for infinite loops

Answer 21

False. Possibly infinite

Question 22

Once the loop finishes, what gets assigned to x.

Answer 22

10

Question 23

What keyword termintates a loop

Answer 23

break

Question 24

What is the difference between while loop and do while loop?

Answer 24

do while will run atleast once and while loop runs from 0 times.

Question 25

How can you define lists

Answer 25

Mutable Ordered Collections

Question 26

What is it meant to be mutable

Answer 26

Can be changed (lists and dictionaries)

Question 27

Are strings mutable

Answer 27

no

Question 28

What prints in the following (REPL)

Answer 28

True.

Question 29

What prints in the following (REPL)

Answer 29

False. The list, [1] is not in the list

Question 30

What is the difference of function and method

Answer 30

Methods usually change what is dotted with it (xs.append(3))

Question 31

What prints in the following REPL

Answer 31

Question 32

True or false? Mutable types store references, not the actual value

Answer 32

True. Assigning something to a mutable type will assign it to the reference. But with a immutable type it essentially "copies" the value

Question 33

What prints in the following REPL

Answer 33

Question 34

What is the difference between the line 3 and: ```>>> ys=xs```

Answer 34

ys=xs will assign ys to xs reference point. But copy will actually copy the values of xs and assign it to ys

Question 35

What is the main difference between tuples and lists

Answer 35

Lists are mutable and tuples are immutable

Question 36

What is the difference between line 6 and line 9

Answer 36

6 appends and changes the list. 9 concatenates and creates a whole new list

Question 37

What is the difference between line 8 and line 10

Answer 37

10 will not give an error