Variables in Python

What is a Variable? A variable is a named location in memory that stores a value. In Python, we can assign values to variables using the assignment operator =. The value of a variable can be changed later in the program.

Creating Variables

Python

x = 10        # integer
name = "Ashish"   # string
price = 99.99     # float
is_valid = True   # boolean

x stores an integer 10.
name stores a string "Ashish".
price stores a float 99.99.
is_valid stores a boolean True.

Note: In Python you don’t need to declare variables before using it, unlike other languages like Java, C etc.

Variable Naming Rules

Can contain letters (uppercase or lowercase), numbers, and underscores (_).
Must start with a letter or an underscore (not a number).
Variable names are case-sensitive (Name and name are different).
Cannot use reserved keywords (like class, def, if, etc.).
Never use special symbols such as !, @, #, $, %, etc.
Whitespace is not allowed inside a variable name.

Example:

Python

age = 25           # valid
_age = 30          # valid
my_name = "Sam"    # valid
2price = 100       # ❌ invalid
class = "test"     # ❌ invalid (keyword)

Re-declare the Variable In Python, re-declaring a variable typically means assigning a new value to an existing variable. Since Python is dynamically typed, you don’t need to explicitly declare the type of variable, so re-declaring it is just reassigning a new value.

Example: Changing the value of a variable.

Python

# Initial declaration
x = 10
print(x)  # Output: 10

# Re-declare the variable by assigning a new value
x = 20
print(x)  # Output: 20

# Re-declare with a different type (Python allows this because it's dynamically typed)
x = "Now I'm a string"
print(x)  # Output: Now I'm a string

Multiple Assignments In Python, we can assign values to multiple variables in a single line.

a) Assigning different values to multiple variables: Python allows adding different values in a single line with “,” operators. We can assign multiple values at once.

Example:

Python

a, b, c = 10, 20, 30
print(a, b, c)   # 10 20 30

b) Assigning a same value to multiple variables: Also, Python allows assigning a single value to several variables simultaneously with “=” operators.

Example:

Python

x = y = z = 100
print(x, y, z)   # 100 100 100

Deleting Variables We can delete a variable using del:

Python

x = 50
del x
# print(x)  # ❌ Error: x is not defined

Checking Variable Type We can use the type() function:

Example:

Python

x = 10
print(type(x))    # 

y = "Hello"
print(type(y))    #

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