Operators and Expressions in Python

🟢 Beginner

📖 Definition

An Operator is a special symbol used to perform calculations, assign values, compare variables, check logical conditions, and inspect object membership or identity. An Expression combines variables, constants, and operators to evaluate a resulting value.

🇮🇳 Hindi

Operators calculations karne, values compare karne, aur logical conditions check karne ke kaam aate hain. Python mein special division operators hote hain: / (float division) aur // (floor/integer division). Membership checking ke liye in aur not in ka use hota hai.

🚩 Marathi

Operators cha wapar calculations, comparison, aani logical checks karnyasathi hoto. List kiva string madhye item shodhnyasathi in aani not in operator vaparatat.

📝 Operator Categories

1. Arithmetic Operators

+ (Add), - (Subtract), * (Multiply)
/ (Float Division): Returns float (10 / 4 -> 2.5)
// (Floor / Integer Division): Truncates decimal part (10 // 4 -> 2)
% (Modulus / Remainder): Returns remainder (10 % 4 -> 2)
** (Exponentiation / Power): 2 ** 3 -> 8

2. Relational / Comparison Operators

== (Equal), != (Not Equal), > (Greater), < (Less), >= (Greater Equal), <= (Less Equal)

3. Logical Operators (Word-based)

and: Returns True if both conditions are true (short-circuits).
or: Returns True if at least one condition is true (short-circuits).
not: Inverts boolean state (not True -> False).

4. Membership Operators (`in`, `not in`)

Checks if a value or substring exists inside a string, list, tuple, or set:

fruits = ["apple", "banana", "cherry"]
print("banana" in fruits) # True
print("z" not in "python")  # True

5. Identity Operators (`is`, `is not`)

Checks if two variables refer to the exact same object in memory (compares id(), unlike == which compares value content).

💡 Complete Example: Operator Evaluation

# Operator Evaluation Demo
total_items = 17
box_capacity = 5

# Division Comparison
boxes_filled = total_items // box_capacity  # 3 (Floor division)
remaining_items = total_items % box_capacity # 2 (Modulus)

print(f"Boxes Filled     : {boxes_filled}")
print(f"Remaining Items  : {remaining_items}")

# Logical & Membership Checking
user_role = "ADMIN"
active_roles = ["ADMIN", "MANAGER", "SUPERUSER"]
is_account_active = True

# Logical Evaluation
can_access_dashboard = (user_role in active_roles) and is_account_active
print(f"Access Allowed?  : {can_access_dashboard}")

# Chained Comparison Syntax (Pythonic Feature!)
age = 22
is_adult_working_age = 18 <= age <= 60 # Equivalent to (18 <= age and age <= 60)
print(f"Working Age?     : {is_adult_working_age}")

👀 Output

Boxes Filled     : 3
Remaining Items  : 2
Access Allowed?  : True
Working Age?     : True

⚠️ Common Mistakes

Using single assignment = instead of comparison == inside if statements.
Confusing == (compares value equality) with is (compares memory object identity).
Expecting integer division / in Python 3 to return an integer (in Python 3, / ALWAYS returns a float! Use // for integer division).

🛡️ Safety / Important Notes

Always use parentheses () when combining multiple and and or logical operations in a single expression to make evaluation order explicit and readable.

🌍 Real-World Usage

E-commerce discount eligibility checks, permission checks in web apps, searching strings/tags using in, and mathematical data analytics.

🧪 Try It Yourself

Test print(10 / 3) vs print(10 // 3).
Test "Py" in "Python" vs "Java" in "Python".

🎯 Mini Challenge

Write an expression using % 2 == 0 that checks whether a given number is even, and combine it with and to check if it is also greater than 10.

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