Ternary Operator in Dart

What is the Ternary Operator?

The ternary operator is a one-line shorthand for simple if-else statements. It is called "ternary" because it takes three operands: condition, true-value, and false-value.

Syntax

condition ? valueIfTrue : valueIfFalse

Example

void main() {
  int age = 20;
  String status = age >= 18 ? 'Adult' : 'Minor';
  print(status);  // Adult

  double price = 100.0;
  bool isMember = true;
  double finalPrice = isMember ? price * 0.9 : price;
  print('Final price: \$$${finalPrice.toStringAsFixed(2)}');  // $90.00

  int x = 5;
  print(x % 2 == 0 ? 'Even' : 'Odd');  // Odd

  // In string interpolation
  bool isDarkMode = false;
  String theme = isDarkMode ? 'dark' : 'light';
  print('Theme: $theme');  // Theme: light
}

Adult
Final price: $90.00
Odd
Theme: light

Nested Ternary

You can nest ternary operators, but use sparingly — it hurts readability:

int score = 75;
String grade = score >= 90 ? 'A'
             : score >= 80 ? 'B'
             : score >= 70 ? 'C'
             : 'F';
print(grade);  // C

⚠️ Common Mistakes

• Using ternary for multi-line logic — use if-else instead.
• Over-nesting ternary operators, making code unreadable.

🧠 Quiz

Summary

The ternary operator condition ? trueValue : falseValue is a concise one-line if-else for simple conditions. Use it when both branches return a value. Avoid nesting more than two levels — use if-else if for complex logic instead.