Python if Statement - Complete Guide with Examples

📚 What You'll Learn Here

What the if statement is — the simplest decision-making tool
Syntax of if — how to write conditional statements
Indentation rules — why indentation matters in Python
Simple conditions — using relational operators
Multiple conditions — using and, or, not
Real-world examples — even/odd, number comparison
Common mistakes — and how to avoid them

What is the if Statement?

The if statement is the simplest and most important decision-making tool in Python. It allows you to execute a block of code only when a certain condition is true. Think of it as a gatekeeper — it checks a condition and decides whether to let the code pass through or skip it.

💡 Key insight: The if statement is the foundation of all conditional logic in Python. Every other decision-making statement builds upon it. Master the if statement, and you've mastered the core of Python's control flow.

A programmer may have to make different choices. These choices execute different Python statements or parts of a script depending on certain conditions. The if statement is used for the conditional execution of statements. It decides whether a certain statement or block of statements will be executed or not — if a given condition is true, then the statements or block of statements is executed; otherwise, it's skipped.

Syntax of if Statement

# Syntax of if Statement
if condition:
    # Body of if
    # Python statements to execute if condition is true

# Example
age = 18
if age >= 18:
    print("You are eligible to vote!")

# Output: You are eligible to vote!

📖 Breaking it down: The if keyword is followed by a condition (an expression that evaluates to True or False). The condition is followed by a colon (:). The body of the if statement is indented (usually 4 spaces). Python evaluates the condition. If it's True, the indented code runs. If it's False, the indented code is skipped.

⚠️ Important: Python uses indentation to define blocks of code. All statements in the body of an if must be indented at the same level. This is different from many other languages that use curly braces {}.

Flowchart of if Statement

Let's visualize how the if statement works using a flowchart:

Flowchart:

    ┌─────────────┐
    │    START    │
    └──────┬──────┘
           ▼
    ┌─────────────┐
    │   Condition │ ◄─── Test the condition
    │   (True?)   │
    └──────┬──────┘
           │
      True │
           ▼
    ┌─────────────┐
    │  Execute    │
    │  Body of if │
    └──────┬──────┘
           │
           ▼
    ┌─────────────┐
    │   END       │
    └─────────────┘

What happens:
1. The flow enters the if statement
2. The condition is tested
3. If True → body of if executes
4. If False → body of if is skipped
5. Program continues with the next statement after if

Simple Condition Example

Let's look at a simple example that checks which number is smaller:

# Find the smaller of two numbers
p = 8
q = 6

if p < q:   # Test condition
    print(p, "is smaller than", q)

if q < p:   # Test condition
    print(q, "is smaller than", p)

# Output:
# 6 is smaller than 8

📖 Explanation: In this example, we used two separate if statements. The first condition p < q evaluates to False (8 is not less than 6), so its body is skipped. The second condition q < p evaluates to True (6 is less than 8), so its body executes and displays the output.

Even or Odd Example

This is a classic example that checks if a number is even or odd using the modulus operator:

# Python script to find if a number is even or odd
n = int(input("Enter Any Number: "))

if n % 2 == 0:
    print(n, "is Even")

if n % 2 == 1:
    print(n, "is Odd")

# Output:
# Enter Any Number: 5
# 5 is Odd

📖 Explanation:
1. n = int(input("Enter Any Number: ")) — accepts user input and converts it to an integer.
2. if n % 2 == 0: — checks if the remainder when divided by 2 is 0. If true, the number is even.
3. if n % 2 == 1: — checks if the remainder is 1. If true, the number is odd.
4. Since 5 % 2 = 1, the second condition is true and "5 is Odd" is displayed.

Multiple Conditions

You can combine multiple conditions using logical operators — and, or, and not:

# Using 'and' operator
age = 25
has_license = True

if age >= 18 and has_license:
    print("You can drive!")

# Using 'or' operator
is_weekend = True
is_holiday = False

if is_weekend or is_holiday:
    print("You can relax!")

# Using 'not' operator
is_raining = False

if not is_raining:
    print("Go outside and enjoy!")

# Output:
# You can drive!
# You can relax!
# Go outside and enjoy!

💡 Remember: When using multiple conditions, parentheses can make your code clearer: if (age >= 18) and (has_license):.

Common Mistakes to Avoid

❌ Mistake 1: Using = instead of ==

This is the most common mistake in conditional statements!

# WRONG (assignment instead of comparison)
if x = 5:  # This will cause a SyntaxError!
    print("x is 5")

# CORRECT (comparison)
if x == 5:
    print("x is 5")

❌ Mistake 2: Missing Colon

Every if statement needs a colon at the end.

# WRONG
if x > 0  # Missing colon!
    print("Positive")

# CORRECT
if x > 0:
    print("Positive")

❌ Mistake 3: Incorrect Indentation

Python relies on indentation to define code blocks. Inconsistent indentation causes errors.

# WRONG (inconsistent indentation)
if x > 0:
print("Positive")  # IndentationError!

# CORRECT (consistent indentation)
if x > 0:
    print("Positive")

Try It Yourself!

Experiment with the if statement directly in your browser. Modify the code and see the results in real time.

Loading Pyodide... 0%

Python Code Editor

========================================
IF STATEMENT
========================================

1. SIMPLE IF
You can vote!

2. EVEN OR ODD
7 is odd

3. MULTIPLE CONDITIONS
10 is between 0 and 20

4. USER INPUT

✅ Explore different if conditions!

🏆

🎉 You've Mastered Python if Statement!

You understand the if statement, syntax, indentation, and how to use conditions. This is the foundation of all decision-making in Python!

Quick Quiz – Test Your Knowledge

Let's see what you've learned about the if statement:

1. What is the correct syntax for an if statement?

A) if condition { } B) if condition: C) if condition then D) if (condition)

2. What happens if the condition in an if statement is False?

A) The body of if executes B) The body of if is skipped C) The program crashes D) The program restarts

3. What is the result of if 5 > 3: print("True")?

A) Nothing is printed B) True is printed C) False is printed D) Error is printed

4. Which operator is used for comparison in an if statement?

A) = B) == C) := D) !=

5. What does the and operator do in a condition?

A) It combines two conditions with OR logic B) It combines two conditions with AND logic C) It reverses a condition D) It compares two values

Frequently Asked Questions

🤔 What is the difference between `=` and `==`?

= is the assignment operator used to assign values to variables. == is the equality operator used to compare two values. Using = in a condition causes a SyntaxError.

🔧 Does Python require indentation in `if` statements?

Yes! Python uses indentation to define code blocks. All statements in the body of an if must be indented at the same level (usually 4 spaces). Inconsistent indentation causes errors.

📐 Can I have multiple `if` statements?

Yes! You can use multiple if statements to check different conditions independently. Each if is evaluated separately, and multiple blocks can execute if their conditions are true.

📊 Can I use logical operators in `if` conditions?

Yes! You can combine conditions using and, or, and not. For example: if age >= 18 and has_license:.

⚡ What happens if the condition is `True`?

If the condition is True, the indented block of code inside the if statement executes. After that, the program continues with the next statement after the if block.

🎯 Can I put another `if` inside an `if`?

Yes! This is called a nested if. The inner if only runs if the outer if condition is true. However, deep nesting can make code hard to read, so use it sparingly.

📚 Where to Go From Here

Now that you've mastered the if statement, here are the next topics to explore:

Previous: Decision Making Next: if-else Statement →

Python

📝 Python if Statement: Complete Guide

What is the if Statement?

Syntax of if Statement

Flowchart of if Statement

Simple Condition Example

Even or Odd Example

Multiple Conditions

Common Mistakes to Avoid

❌ Mistake 1: Using = instead of ==

❌ Mistake 2: Missing Colon

❌ Mistake 3: Incorrect Indentation

Try It Yourself!

🎉 You've Mastered Python if Statement!

Quick Quiz – Test Your Knowledge

Frequently Asked Questions

🤔 What is the difference between `=` and `==`?

🔧 Does Python require indentation in `if` statements?

📐 Can I have multiple `if` statements?

📊 Can I use logical operators in `if` conditions?

⚡ What happens if the condition is `True`?

🎯 Can I put another `if` inside an `if`?

📚 Where to Go From Here

📝 The if-else Statement

📝 The if-elif-else Ladder

📝 Nested if Statements

Python

📝 Python if Statement: Complete Guide

What is the if Statement?

Syntax of if Statement

Flowchart of if Statement

Simple Condition Example

Even or Odd Example

Multiple Conditions

Common Mistakes to Avoid

❌ Mistake 1: Using = instead of ==

❌ Mistake 2: Missing Colon

❌ Mistake 3: Incorrect Indentation

Try It Yourself!

🎉 You've Mastered Python if Statement!

Quick Quiz – Test Your Knowledge

Frequently Asked Questions

🤔 What is the difference between = and ==? ▼

🔧 Does Python require indentation in if statements? ▼

📐 Can I have multiple if statements? ▼

📊 Can I use logical operators in if conditions? ▼

⚡ What happens if the condition is True? ▼

🎯 Can I put another if inside an if? ▼

📚 Where to Go From Here

📝 The if-else Statement

📝 The if-elif-else Ladder

📝 Nested if Statements

🤔 What is the difference between `=` and `==`?

🔧 Does Python require indentation in `if` statements?

📐 Can I have multiple `if` statements?

📊 Can I use logical operators in `if` conditions?

⚡ What happens if the condition is `True`?

🎯 Can I put another `if` inside an `if`?