Statements in Python

Question 1

Variable

Answer 1

• as you write programs you will make up your own words that have meaning to you called VARIABLES
• you can use any name as a variable in python EXCEPT FOR THE RESERVED WORDS
• we use this term Variable to refer to the labels we use to refer to this stored data
• in algebra and symbolic logic- a variable is some unknown that we want to use in either statement, equation, etc.
• (within reason) we can create as many variables as we want
• sometimes we create them because the code needs them. Other times we create them to help us understand (ex. Circumference is d*Pi, but d can also be thought of as 2r)

Question 2

How are python variables similar to variables in algebra?

Answer 2

-just like the familiar variables x and y in mathematics, we use variables in programming to easily manipulate values
-ex.
»> x = 2
»>print(x)
2

(We call the way we used the = sign an assignment operator)

Question 3

What ranges of values do integers have?

Answer 3

Negative really big to positive really big

Question 4

What ranges of values do bools have?

Answer 4

True and false

Question 5

What ranges of values do floats have?

Answer 5

Negative really big to positive really big

Question 6

What ranges of values do strings have?

Answer 6

A really big set of value

Question 7

How do we differentiate between a float and an integer value?

Answer 7

• floats have decimals
• integers are whole numbers

But we can check by using isinstance()
Isinstance(object, classinfo)
Ex.

number=25.9
»>Check_int = isinstance(25.9, int)
»>Print(check_int)
False

Question 8

How can we specify a string value?

Answer 8

• put the sequence of characters inside either single or double quotes
• from there you can assign it to a variable

Ex.
>>>single_quote_character = ‘a’
>>>print(single_quote_character)
a
>>>print(type(single_quote_character))

Question 9

The type function

Answer 9

-the type() method returns class type of the argument(object) passed as a parameter
-mostly used for debugging purposes
-Type(object)
-ex.
»>print(type([]) is list)
True

Question 10

Operators

Answer 10

Are special symbols that represent computations

Question 11

Which operators make sense for integers?

Answer 11

\+
-
*
**
/
// 
%

Question 12

Integer Division Operator

Answer 12

-it always truncates it’s result down to the next smallest integer (to the left on the number line)
-ex.
If we use print(7 / 4)
We would just get the answer as it is. Which is 1.75.
But with the integer division operator,
Print(7 // 4)
It gives us the answer but just that whole number. It doesn’t matter if it was over .5 and could be rounded. It’s at the number it’s at. So our answer for this one would just be 1

Question 13

Modulus Operator

Answer 13

-sometimes also called the remainder operator or integer remainder operator
-it works on integers (and integer expressions) and yields the remainder when the first operand is divided by the second
-in Python, the modulus operator is a percent sign (%)
-ex.
quotient = 7 // 3
With this we would get 2.
But if we did
7 % 3
It gives us the remainder. 6\3 is 2. But with 7, that’s a whole number not accounted for. So we get 1 for the answer
Ex. 32 % 9
We would get 5. Because 9 times 3 is 27. 32-27 = 5. It gives us the remainder

Question 14

Can you use the same operators with integers and floats?

Answer 14

Yes

Question 15

Logical operators you can use in bools

Answer 15

-these operators are and, or, and not

Question 16

Operators for lists

Answer 16

• append(object)
• index(object, start, end)
• count(object)
• reverse()
• clear()
• copy()
• extend(iterable)
• insert(index, object)

And more?? I guess idk there’s a lot

Question 17

Operators for strings

Answer 17

Assignment operator: =
Concatenate operator: +
String repetition operator: *
String slicing operator: []
String comparison operator: “==“ & “!=“
Membership operator: “in” & “not in”
Escape sequence operator: \
String formatting operator: “%” & “{}”

Question 18

Assignment operator

Answer 18

-“=“

Ex.
String1 = “hello”

Question 19

Concatenate Operator

Answer 19

“+”

Ex. 
>>>string1 = “hello”
>>>string2 = “world “
>>>string_combined= string1+string2
>>>print(string_combined)
helloworld

Question 20

String repetition operator

Answer 20

“”
-the same string can be repeated in python by n times using stringn

Ex.
»>string1 = “helloworld”
»>print(string1*2)
helloworld helloworld

Question 21

String slicing operator

Answer 21

“[]”

• characters from a specific index of the string can be accessed with the string[index] operator
• the index is interpreted as a positive index starting from 0 from the left side and negative index starting from -1 from the right side

Ex.
»>string1 = “helloworld”
»>print(string1[1])
e

H e l l o w o r l d
0 1 2 3 4

Question 22

String comparison operator

Answer 22

“==“ and “!=“

“==“ operator returns Boolean True is two strings are the same and return Boolean False is two strings are not the same

“!=“ operator returns Boolean True if two strings are NOT the same and returns Boolean False if two strings are the same

-these operators are mainly used along with if condition to compare two strings where the decision is to be taken based on string comparison

Question 23

Membership operator

Answer 23

“in” and “not in”

• membership operator is used for searching whether the specific character is a part of/member of a given input python string
• they are also useful to find whether specific substring is part of a given string
• “a” in string: returns Boolean true if “a” is in the string
• “a” not in string: returns Boolean true is “a” is NOT in the string

Ex.
»>string1 = “helloworld”
»>print(“w” in string1)
True

Question 24

Escape sequence operator

Answer 24

“\”

• to insert a non-allowed character in the given input string, an escaped character is used
• an escape character is “\” or “backlash” operator followed by a non-allowed character
• an example of a non-allowed character in python string is inserting double quotes in the string surrounded by double quotes

Ex.
Non allowed double quotes in python:
>>>string = “Hello world I am from “India””
>>>print(string)
You would get a syntax error 

Now if you want to make this work use escape sequence operator
»>string = “Hello world I am from \”India\””
»>print(string)
Hello world I am from “India”

Question 25

Functions

Answer 25

-a named sequence of statements inside a function definition

Pg. 47, 53

Question 26

Function Definition

Answer 26

• A statement that creates a new function, specifying its name, parameters, and the statements it executes
• once we define a function, we can reuse the function over and over throughout our program

Question 27

Function call

Answer 27

A statement that executes a function. It consists of the function name followed by an argument list

Question 28

Function object

Answer 28

A value created by a function definition. The name of the function is a variable that refers to a function object

Question 29

How do functions relate to math?

Answer 29

• they (optionally) take an input value (or multiple values) and return something
• these inputs (or parameters or arguments) often need to be of a specific type
• what they return is called a return value. Values must have types

Question 30

<>

Answer 30

-if values of two operands are not equal, then condition becomes true
-ex.
(a <> b) is true. This is similar to the != operator

Question 31

Do equality and inequality operators only work for bools??!

Answer 31

NOOO

they work for strings too!

Question 32

Ternary Operator

Answer 32

• is a way of writing conditional statements in Python
• there are three operands in a ternary operator including:

Condition: a Boolean expression that evaluates to either true or false
True_val: a value to be assigned if the expression is evaluated true
False_val: a value to be assigned if the expression is evaluated false

Ex.
>>>is_nice = True
>>>state = “nice” if is_nice else “not nice”
>>>print(state)
nice