Control Flow

05 / 10 Part of python basic

🔀 Topic 04 · Decisions

Control Flow

Use if/elif/else, match statements, and boolean logic to make your programs intelligent and responsive to data.

⏱ ~35 min
🟢 Beginner
🧠 Logic

if / elif / else

The most fundamental control structure: execute code only when a condition is true.

if_else.py

score = 78

if score >= 90:
    print("Grade: A")
elif score >= 75:
    print("Grade: B")  # ← This runs
elif score >= 60:
    print("Grade: C")
else:
    print("Grade: F")

⚠️ Indentation is the syntax

Python uses 4 spaces to define blocks — there are no curly braces. Inconsistent indentation causes an IndentationError.

Ternary (Inline) if

Write simple conditions on a single line using the ternary expression.

ternary.py

age    = 20
status = "adult" if age >= 18 else "minor"
print(status)  # adult

match Statement (Python 3.10+)

Python's structural pattern matching is similar to switch/case in other languages, but far more powerful.

match.py

command = "quit"

match command:
    case "start":
        print("Starting...")
    case "stop" | "quit":
        print("Stopping...")  # ← Runs
    case _:
        print("Unknown command")

Nested Conditions

Conditions can be nested, but keep it shallow (max 2–3 levels) to preserve readability.

nested.py

has_account = True
is_verified = False

if has_account:
    if is_verified:
        print("Welcome back!")
    else:
        print("Please verify your email")
else:
    print("Please sign up")

Menu

Control Flow

if / elif / else

Ternary (Inline) if

match Statement (Python 3.10+)

Nested Conditions