Conditional Statements

Conditional Statements

What it means

Conditional statements let a program branch — run different code depending on whether a condition is true or false. Python uses if, optional elif (else-if) branches, and an optional final else. Unlike many languages, Python has no switch statement in older versions — chained elif (or match in 3.10+) fills that role.

Examples

age = 20

if age < 13:
    category = "child"
elif age < 20:
    category = "teenager"
else:
    category = "adult"

print(category)   # adult

# Ternary (conditional expression)
status = "even" if age % 2 == 0 else "odd"

# match statement (Python 3.10+)
match category:
    case "child":
        print("Welcome, kid!")
    case "teenager" | "adult":
        print("Welcome!")

Common mistake

Using = (assignment) instead of == (comparison) inside a condition — though Python raises a SyntaxError for this in an if statement (unlike C), the confusion still trips up beginners moving between languages, and the walrus operator := adds a new, easily-mixed-up lookalike.

# SyntaxError in Python -- can't assign inside a plain if condition
# if x = 5:
#     ...

# Correct comparison
if x == 5:
    ...

# The walrus operator DOES assign inside a condition -- different purpose
if (n := len(data)) > 10:
    print(f"{n} items, that's a lot")

Quick practice

1. What keyword does Python use instead of else if?

   Answer

   elif.

2. What’s the result of "yes" if 3 > 5 else "no"?

   Answer

   "no" — the condition 3 > 5 is false, so the ternary returns the value after else.

3. Can you write if x = 5: in Python?

   Answer

   No — that raises a SyntaxError. Use == for comparison; assignment inside a condition requires the walrus operator :=.