W2 - Boolean, Precedence, Intro to Sequences, Type Casting

Question 1

What are True and False equal to?

Answer 1

1 and 0 respectively

Question 2

What is the return type for the expression 4 == x? What are the possible values?

Answer 2

bool, and either True of False (CAPITAL FIRST LETTERS)

Question 3

What will this code yield?
»> myval = 3 < 5
»> myval + 7
_______?

Answer 3

8, the boolean True is equivalent to a 1

Question 4

what are the and/or operators?

Answer 4

literally just the words “and” and “or”

Question 5

order of precedence for operators (highest = top, lowest = bottom)

Answer 5

parentheses
exponentiation
negation
multiplication/division (including modulus)
addition/subtraction
relations (<, >, <=, ==, !=, etc)
not
and
or (nandor!)

Question 6

define associativity

Answer 6

same precedence, therefore move left to right (like PEMDAS)

Question 7

what are the logical operators?

Answer 7

not, and, or (nandor)

Question 8

strings returned with any quotation marks around them are returned with (double/single) marks

Answer 8

single

Question 9

Show the result:
»> myname = ‘monty’
»> len(myname)

Answer 9

5

Question 9

Show the result:
»> myname = ‘monty’
»> myname[0]

Answer 9

would result in ‘m’ (with the single quotation marks)

Question 10

Show the result:
»> 3 in [44, 3, 5, -9]

Answer 10

True (rmr, capital letters!)

Question 11

when should you use snake case?

Answer 11

when describing a unit of a variable in the variable name (ex. timeSinceStarted_ms)

Question 12

Which of the following are true?
1. the = operator is used for both assignments and equality
2. Strings can be compared using the relational operators
3. The first character in a string variable mystring is mystring[1]
4. The len function can be used for both strings and lists

Answer 12

2 and 4 are correct

Question 13

True/false: Strings can be modified

Answer 13

false, they are immutable

Question 14

are lists mutable?

Answer 14

yes!

Question 15

what are sequences?

Answer 15

a type of data structure that orders data in a specific sequence, and can be indexed with integer indices

Question 16

true/false: python shows strings with single or double quotes depending on the data type of the output

Answer 16

false, python ALWAYS shows strings with single quotes unless printed, in which case there are no quotes

Question 17

how would you typecast to:
1. a string
2. a float
3. an integer
4. a boolean

Answer 17

1. str()
2. float()
3. int()
4. bool()

Question 18

what is the value of True? what about False?

Answer 18

False == 0
True is 1 generally, except when converted from a number to a booolean (i.e. bool(4)) which will return True

Question 19

what will int(5.7) return?

Answer 19

5, float —-> int causes the decimal to be truncated

Question 20

what will float(7//2) return?

Answer 20

3.0, returns an integer that is ONLY AFTER COMPLETION turned into a float

Question 21

mixedList = [22, ‘hello’, 4>6]
what will print(mixedList) result in?

Answer 21

[22, ‘hello’, False]

(results, not the equations are stored!)

Question 22

how do you print with quotations?

Answer 22

use the repr() function

print(‘word’, repr(‘word’))
will result in
word ‘word’

Question 23

abd > abcd
abcd > abc
a > A

Answer 23

True, d comes after c and is therefore greater
True, abcd is longer than abc despite having the same first 3 letters
True, lowercase > uppercase

Question 24

how do you remove a already imported library from code?

Answer 24

restart the code environment (restart session in jupyter notebooks)

Question 25

import the choice function from the random library

Answer 25

from random import choice

Question 26

rename the random library to bob, and choice to bill

Answer 26

import random as bob
now you can do bob.random()
from bob import choice as bill
now you can do bob.bill()

Question 27

what does .upper() or .lower() do to a string?

Answer 27

nothing, strings are immutable, thus an external function cannot alter it. only reassignment can change what you get when you print the variable connected to the mem. location

Question 28

what does randint(a, b) do?

Answer 28

creates a random integer between a and b (inclusive)

Question 29

what does choice do?

Answer 29

chooses a random ITEM IN A SEQUENCE! CANNOT BE USED LIKE RANDIN UNLESS THE SEQUENCE IS LITERALLY A LIST OF NUMBERS/STRING OF NUMBERS

Question 30

what does
x = “False”
bool(x) == False
return?

Answer 30

false, you cannot typecast a string to anything but true unless the string is empty (“”)

Question 31

function vs. method

Answer 31

function = nonspecific to a single class, whereas method is an action defined in the class

thus
function = no dot operator, whereas method does

Question 32

How to find last digit of 125? (easiest way)

Answer 32

125%10

Question 33

random vs. random.random()

Answer 33

random is a module, random.random() is a function within that module