Variables

Variables

Table of Contents

• Variables
• Data Types
• Numbers
• Number Methods
• Strings
• Type Conversion
• Python Booleans
• Exercise

• Varibles are used to store values.
• To create a variable, use the equal sign `(=)`.

In the examples below, we create varibales name fruit and name and we assign them values 'mango' and 'viola' respectively

fruit = 'mango'
name = 'voila'

# printing out
print(name, ' likes ', fruit )

voila  likes  mango

Rules to consider

Before choosing a variable name, consider the following.

• Spaces are not allowed in a variable name eg `my age = 34`
• A variable name can not start with number eg `1name = 'Chris'`
• Variable names can not have special characters eg `n@me = 'Comfort'`
• Are case sensitive. Ie Name and name are not the same!

Examples of good variable names

character = 'Peter Griffin'
my_favorite_character = 'Stewie Griffin' # snake case
myFavoriteCharacter = 'Meg Griffin' # camel case
MyFavoriteCharacter = 'Brian Griffin' # Pascal case

Data Types

In this section of the tutorial, you will learn the most basic data types in Python

Numbers

These are two basic types of numbers and they are called:

• integer(numbers without decimal places)
• floating point numbers(numbers with decimal places)

# python numbers
# Integers
age = 45
population = 45000000

# Floating point numbers
height = 1.7
weight = 147.45

Find More on Numbers Here

Strings

Strings are simply text. A string must be surrounded by single or double quotes

# Strings
name = 'Juma'
other_name = "Masaba Calvin"
statement = 'I love coding'

Find More on Strings Here

Booleans

Boolean data type can only have on fo these values: True or False

Booleans are often the result of evaluated expressions.

Forexample, when you compare two numbers, Python evaluates the expression and returns either True or False

print(5 == 5)
print(10 > 5)
print(20 < 10)

True
True
False

These are often used in if statments.

In this example, if the value of the variable age is more than 18, the program will tell the user that they are allowed to enter

age = 19

if age > 18:
    print('You are allowed to enter.')

You are allowed to enter.

Checking the Type of a Boolean

We can check the data type of a Boolean variable using the type() method.

married = True
print(type(married))

<class 'bool'>

Lists

• A list is an ordered collection of data
• It can contain strings, numbers or even other lists
• Lists are written with square brackets (`[]`)
• The values in lists (also called elements) are separated by commas (`,`)

# Lists
names = ['juma', 'john', 'calvin']
print(names)

['juma', 'john', 'calvin']

Find More on Lists Here

A list can contain mixed data types

other_stuff = ['mango', True, 38]
print(other_stuff)

['mango', True, 38]

Checking data types

To check the data type of an object in python, use type(object), for example, below we get the data type of the object stored in names

# Which data type
print(type(names))

list

Converting Types

Convert to String

The str() method returns the string version of a given object

# convert an integer to a string
age = 45
message = 'Peter Griffin is '+ str(age) + ' years old'
print(message)

Peter Griffin is 45 years old

Convert to Integer

The int() method returns the integer version of the given object.

# Convert floating point to integer
pi = 3.14159
print(int(pi))

3

Convert to Float

The float() method returns the floating point version of the given object.

side = 4
print(float(side))

4.0

Exercise

Write a program to assign the number 34.5678 to a variable named “number” then display the number rounded to the nearest integer value.

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