Python Variables

Variables are containers that store information that can be manipulated and referenced later by the programmer within the code.

In python, the programmer does not need to declare the variable type explicitly, we just need to assign the value to the variable.

Example:

name = "Maxon"   #type str
age = 25            #type int
passed = True       #type bool

 

It is always advisable to keep variable names descriptive and to follow a set of conventions while creating variables:

• Variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
• Variable name must start with a letter or the underscore character.
• Variables are case sensitive.
• Variable name cannot start with a number.

Example:

Color = "yellow"    #valid variable name
cOlor = "red"       #valid variable name
_color = "blue"     #valid variable name

5color = "green"    #invalid variable name
$color = "orange"   #invalid variable name

 

Sometimes, a multi-word variable name can be difficult to read by the reader. To make it more readable, the programmer can do the following:

Example:

NameOfCity = "Mumbai"       #Pascal case
nameOfCity = "Berlin"       #Camel case
name_of_city = "Moscow"     #snake case

 

Scope of variable:

The scope of the variable is the area within which the variable has been created. Based on this a variable can either have a local scope or a global scope.

Local Variable:

A local variable is created within a function and can be only used inside that function. Such a variable has a local scope.

Example:

icecream = "Vanilla"    #global variable
def foods():
    vegetable = "Potato"    #local variable
    fruit = "Lichi"         #local variable
    print(vegetable + " is a local variable value.")
    print(icecream + " is a global variable value.")
    print(fruit + " is a local variable value.")

foods()

Output:

Potato is a local variable value.
Vanilla is a global variable value.
Lichi is a local variable value.

 

Global Variable:

A global variable is created in the main body of the code and can be used anywhere within the code. Such a variable has a global scope.

Example:

icecream = "Vanilla"    #global variable
def foods():
    vegetable = "Potato"    #local variable
    fruit = "Lichi"         #local variable
    print(vegetable + " is a local variable value.")

foods()
print(icecream + " is a global variable value.")
print(fruit + " is a local variable value.")

Output:

Potato is a local variable value.
Vanilla is a global variable value.