Lesson 14: Ternary Operator

Ternary Operator (Conditional Expressions)

The ternary operator, also known as a conditional expression, is a concise way to assign a value based on a condition. It's perfect for simple if-else logic in a single line.

Python's ternary operator syntax is: value_if_true if condition else value_if_false

Basic Ternary Operator

The simplest use case is assigning a value based on a condition:

ternary.py
age = 20
status = "Adult" if age >= 18 else "Minor"
print(status)  # Output: Adult

# Equivalent if-else statement:
if age >= 18:
    status = "Adult"
else:
    status = "Minor"

Common Use Cases

Ternary operators are great for simple conditional assignments. Here are some practical examples:

examples.py
# Check if number is even or odd
x = 10
result = "Even" if x % 2 == 0 else "Odd"

# Find the maximum of two numbers
a = 5
b = 10
maximum = a if a > b else b

# Set a default value if variable is None
name = None
display_name = name if name else "Guest"

# Check if number is positive, negative, or zero
number = -5
sign = "Positive" if number > 0 else ("Negative" if number < 0 else "Zero")

Nested Ternary Operators

You can nest ternary operators for multiple conditions, but be careful - they can become hard to read:

nested.py
score = 85

# Nested ternary (can be hard to read)
grade = "A" if score >= 90 else ("B" if score >= 80 else ("C" if score >= 70 else "F"))

# Better: Use if-elif-else for complex conditions
if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
else:
    grade = "F"

Using Ternary in Function Calls

Ternary operators are particularly useful when passing values to functions:

function_calls.py
count = 1
item_word = "item" if count == 1 else "items"
print(f"You have {count} {item_word}")

# Or directly in the f-string
print(f"You have {count} {'item' if count == 1 else 'items'}")

Best Practices

✅ Use Ternary For Simple Cases

Use ternary operators for simple, one-line conditional assignments. They make code more concise and readable.

⚠️ Avoid Nested Ternaries

Avoid deeply nested ternary operators. Use if-elif-else statements for complex conditions - they're much more readable.

💡 Readability First

If a ternary operator makes your code harder to understand, use a regular if-else statement instead. Readability is more important than brevity.

Comparison: Ternary vs If-Else

Here's when to use each approach:

comparison.py
# Simple condition - Ternary is perfect
status = "Active" if is_active else "Inactive"

# Complex condition - Use if-else
if age >= 18 and has_license and insurance_valid:
    status = "Can drive"
elif age >= 16:
    status = "Can learn"
else:
    status = "Too young"

Ternary Operator