Python Variable

 

Variable

A variable is a container for a value. It can be assigned a name, you can use it to refer to it later in the program.

Based on the value assigned, the interpreter decides its data type. You can always store a different type in a variable.

For example, if you store 5 in a variable, later, you can store ‘Balaji’.

1. Python Variables Naming Rules

There are certain rules to what you can name a variable(called an identifier).

Python variables can only begin with a letter(A-Z/a-z) or an underscore(_).

Program:1

answer=4 answer # Scripts Ends

Output:

4

Program:2

9lives=9 # Scripts Ends

Output:

SyntaxError: invalid syntax

The rest of the identifier may contain letters(A-Z/a-z), underscores(_), and numbers(0-9).

Program:3

year2021_='Good' year2021 # Scripts Ends

Output:

Good

Python is case-sensitive, and so are Python identifiers. Name and name are two different identifiers.

Program:4

name='Balaji' Name # Scripts Ends

Output:

NameError: name ‘Name’ is not defined

2. Assigning and Reassigning Python Variables

To assign a value to Python variables, you don’t need to declare its type.

You name it according to the rules stated in section 2a and type the value after the equal sign(=).

Like a=3,Bob=7,age=75 etc...

3. Multiple Assignment

You can assign values to multiple Python variables in one statement.

Or you can assign the same value to multiple Python variables.

Program:5

Zip,city=88901,'las vegas' print(Zip,city) #same value to multiple Python variables. age_Bob=age_david=40 print(age_Bob,age_david) # Scripts Ends

Output:

88901 las vegas 40 40

4. Swapping Variables

Swapping means interchanging values. To swap Python variables, you don’t need to do much.

Program:6

colour_1,colour_2='red','blue' colour_1,colour_2=colour_2,colour_1 print(colour_1,colour_2) # Scripts Ends

Output:

blue red

5. Deleting Variables

You can also delete Python variables using the keyword ‘del’.

Program:7

Colour_1='red' del Colour_1 Colour_1 # Scripts Ends

Output:

NameError: name 'Colour_1' is not defined

Reserved Words (Keywords)

The following identifiers are used as reserved words, or keywords of the language, and cannot be used as ordinary identifiers. They must be typed exactly as written here:

and	def	False	import	not	True
as	del	finally	in	or	try
assert	elif	for	is	pass	while
break	else	from	lambda	print	with
class	except	global	None	raise	yield
continue	exec	if	nonlocal	return