Conditional Statements in Python

Every program needs to make decisions. In Python, conditional statements allow your program to execute different code blocks based on certain conditions.

This article explains how to use if, elif, and else statements, including nested conditions and short-hand if expressions for compact logic.

What Are Conditional Statements?

A conditional statement evaluates an expression and executes a specific block of code depending on whether the condition is True or False. Python uses the following keywords for conditional logic:
if
elif (short for else if)
else

The if Statement

The if statement is used to test a single condition. If the condition evaluates to True, the code inside the if block executes.

Syntax:

if condition:
    statement(s)

Example:

age = 18

if age >= 18:
    print("You are eligible to vote.")

Output:

You are eligible to vote.

Note: The indentation (space before statements) defines the scope of the if block in Python.

The if-else Statement

Sometimes, you want to execute one block when the condition is True and another when it is False. In such cases, use an if-else structure.

Syntax:

if condition:
    statement(s)
else:
    statement(s)

Example:

num = 5

if num % 2 == 0:
    print("Even number")
else:
    print("Odd number")

Output:

Odd number

The if-elif-else Ladder

When you have multiple conditions, you can use the if-elif-else ladder. The program checks conditions from top to bottom and executes the first one that is True.

Syntax:

if condition1:
    statement(s)
elif condition2:
    statement(s)
elif condition3:
    statement(s)
else:
    statement(s)

Example:

marks = 82

if marks >= 90:
    print("Grade: A")
elif marks >= 75:
    print("Grade: B")
elif marks >= 60:
    print("Grade: C")
else:
    print("Grade: D")

Output:

Grade: B

Only one block executes — the first one whose condition evaluates to True.

Nested if Statements

You can place an if statement inside another if block. This is known as a nested if. It's useful for checking multiple levels of conditions.

Example:

age = 25
citizen = True

if age >= 18:
    if citizen:
        print("Eligible to vote.")
    else:
        print("Not a citizen, cannot vote.")
else:
    print("Not eligible due to age.")

Output:

Eligible to vote.

Use nesting only when necessary — too many nested levels can make code harder to read.

Short-Hand if Expressions

Python allows you to write if statements in a single line when there’s only one statement to execute.

Example 1: Single-line if

x = 10
if x > 5: print("x is greater than 5")

Output:

x is greater than 5

Example 2: Short-hand if-else (Ternary Operator)

a = 10
b = 20

print("a is greater") if a > b else print("b is greater")

Output:

b is greater

This one-liner is often called the ternary expression in Python.

Logical Operators in Conditions

You can combine multiple conditions using and, or, and not inside if statements.

Example:

age = 22
has_license = True

if age >= 18 and has_license:
    print("You can drive.")
else:
    print("You cannot drive.")

Output:

You can drive.

Summary

Conditional statements form the decision-making backbone of Python programming. With if, elif, else, and nested conditions, you can control program flow and handle multiple scenarios efficiently.

In the next article, we'll explore Loops in Python — including for and while loops, range() function, and how to use break and continue effectively.