If Statements

Make decisions with if and else

If Statements — Making Decisions in Code

What Is It?

Programs don't just run line by line — they make decisions. if statements let your code check a condition and run different code depending on whether it's True or False. This is how programs "think."

� **Analogy:** An `if` statement is like a bouncer at a club. If you're on the list (condition is True), you get in. If not, you don't.

Syntax

python

age = 18

if age >= 18:
    print("You can vote!")
else:
    print("Too young to vote.")

Part	What it's called	What it does
`if`	Keyword	Starts the decision block
`age >= 18`	Condition	An expression that evaluates to True or False
`:`	Colon	Marks the end of the condition — don't forget it!
`print(...)`	Body	Indented code that runs only if condition is True
`else:`	Alternative	Optional — runs when condition is False

How It Works

python

temperature = 30

if temperature > 25:
    print("It's hot outside!")
else:
    print("It's cool outside.")

Step by step:

Python checks: is `30 > 25`? → **True** ✅

Since True, it runs the indented block: `print("It's hot outside!")`

It **skips** the `else` block entirely

If temperature were 20 instead, Python would check 20 > 25 → False ❌, skip the if block, and run the else block instead.

� **Indentation matters!** The indented code under `if` and `else` is the **body**. Python uses indentation (usually 4 spaces) to know which code belongs to which block.

Comparison Operators

Operator	Meaning	True Example
`==`	Equal to	`5 == 5`
`!=`	Not equal to	`5 != 3`
`<`	Less than	`3 < 5`
`>`	Greater than	`5 > 3`
`<=`	Less than or equal	`5 <= 5`
`>=`	Greater than or equal	`5 >= 3`

️ **Don't confuse `=` and `==`!** `=` assigns a value. `==` checks equality. This is the #1 beginner mistake.

Why Use Conditionals?

Every interactive program needs decisions:

**Login systems** — "Is the password correct?"

**Games** — "Is the player's health zero? Game over!"

**E-commerce** — "Is the item in stock? Show 'Add to Cart'"

**Validation** — "Is the email format valid?"

Common Mistakes

❌ Wrong	Why	✅ Right
`if age = 18:`	`=` is assignment, not comparison	`if age == 18:`
`if age >= 18` (no colon)	Colon is required at end of condition	`if age >= 18:`

| if age >= 18: with no indented body | Indentation defines the block | `if age >= 18:

print(...)` |

`if (age >= 18)`	Extra parens work but aren't needed in Python	`if age >= 18:`

Your Turn!

Create a variable age = 16. Write an if/else statement that prints "Adult" if age is 18 or older, and "Minor" otherwise.

💡Need a hint? (3 available)

#1Use >= for checking 'greater than or equal to'

#2Don't forget the colon : after the condition

#3Indent the body with 4 spaces

🔑Show solution (try it yourself first!)

age = 16
if age >= 18:
    print("Adult")
else:
    print("Minor")

✏️ Code Editor

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📤 Output

Write your solution and click "Run Code" to test it!

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