The if statement runs a block of code only when its condition evaluates to a truthy value, and is the basic building block of conditional logic in Python.

Syntax

if condition:
    # code runs if condition is truthy

Deep Dive Course

Python's if statement tests any expression for truthiness — not just booleans — so an if can directly test a number, string, or collection without an explicit comparison, since 0, empty strings, and empty collections are all falsy. Unlike many languages, Python has no braces or parentheses around the condition; instead, indentation itself defines which statements belong to the block, making consistent indentation a syntactic requirement, not just a style choice.

1Understanding if Statement

💡

Test truthiness directly, e.g. `if items:`, instead of comparing to an empty value explicitly, e.g. checking that its length is greater than zero — it's more idiomatic and works uniformly across strings, lists, dicts, and other falsy-aware types.

editor.html

age = 20
if age >= 18:
    print("You can vote")

localhost:3000

2Practical Example

Here is a real-world application of if Statement showing how it is used in production Python code.

editor.html

user_input = []
if user_input:
    print("Processing input")
else:
    print("No input provided")

localhost:3000

3Best Practices

Follow these guidelines when working with if Statement:

1. Rely on Python's truthiness rules (if value:) instead of explicit comparisons to True, False, or empty containers

2. Keep condition expressions simple and readable — extract a well-named boolean variable or helper function for complex conditions

3. Use a guard clause to reduce nesting instead of wrapping the main logic in a large if block

⚠️

Tip: Test truthiness directly, e.g. `if items:`, instead of comparing to an empty value explicitly, e.g. checking that its length is greater than zero — it's more idiomatic and works uniformly across strings, lists, dicts, and other falsy-aware types.

editor.html

age = 20
if age >= 18:
    print("You can vote")

localhost:3000

Examples

Example 01Basic Usage

age = 20
if age >= 18:
    print("You can vote")

Example 02Advanced Example

user_input = []
if user_input:
    print("Processing input")
else:
    print("No input provided")

Best Practices

Rely on Python's truthiness rules (if value:) instead of explicit comparisons to True, False, or empty containers
Keep condition expressions simple and readable — extract a well-named boolean variable or helper function for complex conditions
Use a guard clause to reduce nesting instead of wrapping the main logic in a large if block

Interview Question

Why can you write `if some_list:` in Python instead of explicitly checking that its length is greater than zero?▼

Hint: Think about how Python evaluates truthiness for different types.

Python's if statement doesn't require a boolean — it calls bool() on the condition, and every built-in container defines its truthiness through a length or boolean dunder method, treating an empty list, string, or dict as falsy and a non-empty one as truthy. This makes testing the collection directly both more idiomatic and functionally identical to checking its length explicitly, without the extra call.

Exercises

MediumPractice using if Statement in a real scenario.

View Solution

age = 20
if age >= 18:
    print("You can vote")

Frequently Asked Questions

Why can you write `if some_list:` in Python instead of explicitly checking that its length is greater than zero?▼

Related Functions

elif-statementelse-statementbooleans