Python Operators and Expressions

In Python, operators are special symbols or keywords that perform operations on variables and values. When combined with variables or literals, these form expressions, which are the core building blocks of logic and computation in your code.

Example:

x = 10
y = 5
result = x + y  # Expression: x + y

Here, + is the operator, x and y are operands, and x + y is the expression.

Types of Python Operators

Python supports several categories of operators. Let’s explore each one with examples:

Arithmetic Operators

Used for mathematical calculations.

Example:

a = 7
b = 2
print(a + b)  # 9
print(a ** b) # 49
print(a % b)  # 1

Assignment Operators

Used to assign or update values in variables.

Example:

x = 5
x += 3  # Now x is 8
print(x)

Comparison Operators

Used to compare values. They return True or False.

Example:

a = 10
b = 5
print(a > b)   # True
print(a == b)  # False

Logical Operators

Used to combine multiple conditions.

Example:

x = 7
print(x > 5 and x < 10)  # True
print(not(x == 7))       # False

Membership Operators

Check if a value exists in a sequence (like a list or string).

Example:

word = "banana"
print("a" in word)     # True
print("x" not in word) # True

Identity Operators

Check if two variables refer to the same object in memory.

Example:

a = [1, 2, 3]
b = a
c = [1, 2, 3]
print(a is b)      # True
print(a is c)      # False

What Are Expressions?

An expression is a combination of variables, literals, and operators that evaluates to a value.

a = 5
b = 3
c = (a * b) + 2   # This is an Expression: (5 * 3) + 2 = 17
print(c)

Expressions can be used in assignments, conditions, loops, and function calls.

Operator Precedence (Order of Operations)

Python follows standard math rules (PEMDAS) for evaluating expressions.

Use parentheses to ensure the desired evaluation order.

Example:

a = 10
b = 4
c = 2
result = (a + b) * c / 2 - b
print("Result:", result)

Mini Quiz

• What is the output of 5 + 2 * 3?
•   What does not(True and False) return?
•   Is "p" in "Python" True or False?
•   What’s the difference between == and is?

Summary

• Operators perform actions on variables and values.
• Expressions combine operators and values to compute results.
• Use parentheses to control the order of operations.
• Know the difference between equality (==) and identity (is).
• Python supports arithmetic, comparison, logical, assignment, membership, and identity operators.

Coming Up Next

In the next lesson, we’ll dive into Control Flow Statements like if, else, and elif, and learn how to make decisions in Python programs.