Python Variables

Variables are created when we assign a value to it, variables are used to store values. When a variable is created the interpreter will automatically allocate memory based on the datatype. In python, we do not need to declare or define a variable before using them, In Python the variable declaration happens automatically when you assign a value to a variable

Example:

name = "Neural Beast"

Here “name” is the variable and “Neural Beast” is the value assigned to the variable “name”, the assignment is done with (=) equal sign.

Rules for variables name in python

• A variable names are case-sensitive.(eg: Hello and hello are different)
• The variable name must begin with an alphabet or underscore.
• The first character of a variable cannot be a digit.
• A variable name must not contain any special character like !, @, #, %, &, *, ^ and white-space.
• A variable name can contain an lower-case(a-z), upper-case(A-Z), digit(0-9) and underscore.
• A variable name cannot be a keyword.

In python we can use single quotes, double quotes and triple quotes to assign a string value to a variable.

Example:

A = 'Hello'
B = "Hello"
C = """Hello"""
print(A)
print(B)
print(C)

Output:

Hello
Hello
Hello

Keywords

Keywords have special meaning to the language compiler, keywords are reserved words. In python there are 33 reserved keywords in 3.7 version they are,

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

Global Variable

When a variable is created outside of a function, then it is a global variable.

Example:

A = "Neural Beast"
def myfun():
 print(A, "Always Deliver More Than Expected")
myfun():

Output:

Neural Beast Always Deliver More Than Expected

We can also create Global variable inside a function using “global” keyword.

Example:

def myfun():
 global a
 a = "Neural Beast"
myfun()
print(a, "Always Deliver More Than Expected")

Output:

Neural Beast Always Deliver More Than Expected

Python provides type() function which returns the type of the variable passed.

Example:

A = 25
B = 12.3
C = "Neural Beast"
D = True
print(type(A))
print(type(B))
print(type(C))
print(type(D))

Output:

<class 'int'>
<class 'float'>
<class 'str'>
<class 'bool'>

Python provides id() function, which is used to identify the object identifier. Each object has its unique id.

A = "Neural Beast"
B = 12
print(id(A))
print(id(B))

Output:

6285416
1687025760