Python - Creating Variables and Assigning Values Part-1

 Creating Variables and Assigning Values  Part 1

To create a variable in Python, all you need to do is specify the variable name, and then assign a value to it.

<variable name> = <value>

Python uses "=" to assign values to variables. There's no need to declare a variable in advance (or to assign a data type to it), assigning a value to a variable itself declares and initializes the variable with that value. There's no way to declare a variable without assigning it an initial value.

# Integer

a = 2

print(a)

# Output: 2

# Integer

b = 9223372036854775807

print(b)

# Output: 9223372036854775807

# Floating point

pi = 3.14

print(pi)

# Output: 3.14

# String

c = 'A'

print(c)

# Output: A

# String

name = 'John Doe'

print(name)

# Output: John Doe

# Boolean

q = True

print(q)

# Output: True

# Empty value or null data type

x = None

print(x)

# Output: None

Variable assignment works from left to right. So the following will give you an syntax error.

0 = x

=> Output: SyntaxError: can't assign to literal

You can not use python's keywords as a valid variable name. You can see the list of keyword by:

import keyword

print(keyword.kwlist)

Rules for variable naming:

1. Variables names must start with a letter or an underscore.

x = True # valid

_y = True # valid

9x = False # starts with numeral

=> SyntaxError: invalid syntax

$y = False # starts with symbol

=> SyntaxError: invalid syntax

2. The remainder of your variable name may consist of letters, numbers and underscores.

has_0_in_it = "Still Valid"

3. Names are case sensitive.

x = 9

y = X*5

=>NameError: name 'X' is not defined