Python If Statements

If statements let your program choose different paths based on data. This is the foundation of “logic” in programming.

The core idea

• A condition evaluates to either True or False
• If True, Python runs the indented block

Basic if

age = 18

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

Expected output:

You can vote.

if / else

temperature = 75

if temperature > 80:
    print("It's hot in Phoenix.")
else:
    print("Nice weather in Seattle.")

Expected output:

Nice weather in Seattle.

if / elif / else

score = 85

if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
else:
    print("Grade: F")

Expected output:

Grade: B

Comparisons you must know

x = 10
print(x == 10)
print(x != 5)
print(x > 5)
print(x <= 10)

Expected output:

True
True
True
True

Logical operators: and / or / not

age = 25
has_license = True

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

Expected output:

You can drive.

Graph: decision flow

flowchart TD
  A[Check condition] --> B{True?}
  B -->|Yes| C[Run block]
  B -->|No| D[Skip or next condition]

In the next lesson, you will learn loops so you can repeat actions without copying and pasting code.