Module 2

Question 1

variable

Answer 1

a storage location with a name. Each variable has a name and holds a value

Question 2

Why is a variable similar to/compared to a parking space?

Answer 2

Parking space has an identifier and contents like a variable in a computer program

Question 3

assignment statement

Answer 3

stores a value in a variable, aka you use it to place a value into a variable

Question 4

example of an assignment statement

Answer 4

cansPerPack = 6

The left-hand side of an assignment statement consists of a variable. The right-hand side an expression that has a value. That value is stored in the variable.

Question 5

When is a variable created

Answer 5

the first time it is assigned a value

Question 6

What happens if you assign a value to an already existing variable?

Answer 6

It replaces the previously stored value

Question 7

True or False: The assignment operator = does denote mathematical equality

Answer 7

FALSE: It does NOT denote mathematical equality. Assignment is an instruction to do something – namely, place a value into a variable, not the equal symbol in algebra to denote equality.

Question 8

data type

Answer 8

1. determines how the data is represented in the computer and what operations can be performed on that data.
2. Specifies how the value is stored in the computer and what operations can be performed on the value.

Question 9

primitive data type

Answer 9

a data type provided by the language itself

Question 10

What data types does Python support?

Answer 10

numbers, text, strings, files, containers, and many others.

Question 11

Integer

Answer 11

In python it is called int

Whole numbers without a fractional part. No fractions or decimals.

Question 12

floating-point numbers

Answer 12

called float in Python

unlike integers (whole numbers), they are fractional numbers (such as 0.555)

OR

numbers with exponential notation

Question 13

float vs int in Python

Answer 13

float is a floating-point number/value (fractional numbers or numbers with exponential notation)

int is an integer value/number (whole numbers)

Question 14

Number literal

Answer 14

a fixed value in a program this is explicitly written as a number, such as -2 or 6.02214115E23

can be an integer or floating point number

Question 15

Why should you always store values of the same type once a variable is initialized?

Answer 15

It helps avoid error in your code.

Example:

taxRate = 5.0

Although the number is a whole number, it is stored as a floating point number because you can get a fractional number later in your code. This avoids error by all number being unified by using floating point numbers and not a mix of integers and floating point numbers.

Question 16

Naming something in Python rules:

Answer 16

1. Names must start with a letter or an underscore, and remaining characters must be letters, numbers, or underscores.
2. You cannot use symbols such as ? or %. Spaces are not permitted. You can use uppercase letters to denote word boundaries, as in cansPerPack.
3. Names are case sensitive

4.You cannot used reserved words (words reserved for their special Python meanings), such as if or class.

Question 17

Why should you start names with a lower case?

Answer 17

Names that are all uppercase indicate constants, and names that start with an uppercase letter are commonly used for user-defined data types.

Question 18

Constant/constant variable

Answer 18

a value that should not/cannot by changed by a program. In Python, constants customarily have names consisting of all uppercase letters.

Question 19

Comments

Answer 19

an explanation to help the human reader understand a section of a program; ignored by the interpreter.

uses a hashtag(#)

Question 20

Why are comments a good practice?

Answer 20

It helps programmers who read your code understant your intent.

Question 21

magic number

Answer 21

a numeric constant that appears in your code without explanation

Question 22

Why should you avoid magic numbers

Answer 22

In rare circumstances, a constant may need to change. If so a magic number would need to be manually changed. It also provides more descriptive factors.

Question 23

What arithmetic operations can Python run?

Answer 23

the four basic ones as a calculator: addition, subtraction, multiplication, and division

Question 24

** in python

Answer 24

to show when something is to the power of something

Question 25

// in python

Answer 25

division, but it discards the remainder (fractional) to keep it an integer

Question 26

floor division

Answer 26

Taking the quotient of two integers and discarding the remainder. In Python the // symbol denotes floor division.

Ex: 11//4 is 2, not 2.75

Question 27

abs in Python

Answer 27

returns the literal/absolute value

example

abs (-10) will return the value as 10

Question 28

round in Python

Answer 28

when presented with one argument, it will round to the nearest integer. When presented with 2 arguments, it will use the second argument to specify the desired number of fractional digits

Example:

1 argument: round (2.555) -> 3
2 arguments:
round (2.555, 2) -> 2.56 OR
round (2.555[, 2]) -> 2.56

Question 29

min in Python

Answer 29

sets variables to the lowest number in the functions arguments. It takes an arbitrary number of arguments.

example: cheapest = min (5, 20, 13, 10)
cheapest would be set to 5

Question 30

max in Python

Answer 30

sets variables to the largest number in the functions arguments. It takes an arbitrary number of arguments.

example: cheapest = max (5, 20, 13, 10)
cheapest would be set to 20

Question 31

Return Value

Answer 31

The value returned by a method or function through a return statement. Can be used anywhere a literal value can be used.

Question 32

Literal

Answer 32

a notation for a fixed value in a program, such as 2, 3.24, 6.00034E23, “Harry”, or “H”

Question 33

library

Answer 33

a collection of code that has been written and translated by someone else, ready for you to use in your program

Question 34

standard library

Answer 34

a library that is considered part of the language and must be included with any Python system

Question 35

from in Python

Answer 35

used to call a module from the program’s library

Question 36

import in Python

Answer 36

used to import a function from a library in your program

Question 37

built-in functions

Answer 37

functions that are defined as part of the language itself and can be used directly in your programs. Can be used without importing any module

Question 38

True or False: You can combine arithmetic and assignments in Python?

Answer 38

Yes, typically for short cuts

example:

total*=1 —-> total = total * 2

Question 39

strings

Answer 39

a sequence of characters

ex: “Hello” is a sequence of five characters

Question 40

string literal

Answer 40

denotes as a particular string (such as “hello”)

specified by enclosing a sequence of characters within a matching pair of either single or double quotes

Question 41

length in Python

Answer 41

the number of string characters in a string

ex: “hello” has a length of 5

Question 42

len in Python?

Answer 42

len function is the length, and is used to compute the length of a string

Question 43

empty string

Answer 43

a string of 0 is called an empty string. Usually written as “ “ or ‘ ‘

Question 44

concatenate/concatenation

Answer 44

placing one string after another to form a new string

ex:

firstName = Freya
lastName = Rios
name = firstName + lastName —> Freya Rios

Question 45

How do you concatenate strings

Answer 45

with the + operator

Question 46

How can you repeat strings

Answer 46

using the * operator, the number of repetitions must be an integer

Question 47

str in Python

Answer 47

converts an integer to floating-point value to a string

ex:
str(123) —> “123”

Question 48

Unicode

Answer 48

A standard code that assigns code values consisting of two bytes to characters used in scripts around the world. Python stores all characters as their Unicode values.

Question 49

What are strings sequences of?

Answer 49

Sequences of unicode characters.

Question 50

How are string positions counted

Answer 50

string positions are counted starting with 0.

Question 51

index

Answer 51

Position of a character within a string

Question 52

How do you access an individual character to find the position of

Answer 52

with brackets

example:

name= “Harry”

first = name [0]
last = name [4]

Question 53

len function in Python

Answer 53

can be used to determine the position of the last index/ the last character in a string