3. Variables in Python

What are Variables?

Variables are containers that store temporary values or information in computer memory. To use a variable in a program, you must declare a variable.

What do we mean by declaring a Variable in Python?

In Python, the moment we store any information or value in a variable, the variable is declared. We can use variables in a program once we declare them or store a value in them. There are two most important entities to declare a variable: a. Variable name b. Value

For Example:

In [1]:

age = 10
print(age)

10

Here, 10 is a value stored in a variable named age. This is how we declare a Variable in Python.

Naming Convention in Variable:

There are some rules and best practices to follow while naming a variable:

Rule 1: Variables are Case-Sensitive. It means a variable with lowercase is different than the variable in upper case.

In [2]:

age = 10
Age = 20
AGE = 30
print(age,Age,AGE)

10 20 30

Rule 2: We cannot name a variable starting with a digit. 1age = 10 will give an error.

In [3]:

1age = 20

  File "<ipython-input-3-ef3a9e7a157c>", line 1
    1age = 20
     ^
SyntaxError: invalid syntax

Rule 3: We cannot use whitespaces or any symbol while naming a variable, though an underscore is allowed (_). For Example -

• a ge = 10 , @%age=10 will give error

• _age = 10 , voting_age = 18 is good.

In [1]:

_company = "Console Flare"
company_name = "ConsoleFlare"
print(_company,company_name)

Console Flare ConsoleFlare

Best Practice: While naming a variable, keep in mind to give variables a meaningful name. a = 10 does not give a clearer message than age = 10

How to assign or store multiple values in multiple variables:

To assign multiple values in multiple variables, we can simply write them in a single line of code using commas. For Example:

In [2]:

company , company_member = "Console Flare",5000
print(company,company_member)

Console Flare 5000

How to assign a single Value in multiple variables:

To assign a single value in multiple variables , we can simply write them in a single line of code using = sign. For Example:

In [3]:

company = firm = startup = "Console flare"
print(company,firm,startup)

Console flare Console flare Console flare

How to change a value of a variable:

Suppose there is a variable named age with value 10 , we will write it like this (age = 10) to change the value of variable we will again store another value to the same variable. for Example:

In [4]:

age = 10
print(age)
age = 20
print(age)

10
20

Assignment:

• Create a variable and store any numerical value.

• Change the value stored in a variable.

• Store 10,20,30 in three different variables in a single line.

• Store 10 in three different variables in a single line.