Dart -2 Relational Operators and Logical Operators, If else, Ternary, and Switch

🔍 Dart Conditional Statements: if, else, ternary & switch

In this lesson, you’ll learn how to make decisions in Dart using conditions. We start by understanding relational and logical operators.

📊 Relational Operators in Dart

Operator	Description	Example (a=5, b=3)	Result
==	Equal to	a == b	false
!=	Not equal to	a != b	true
>	Greater than	a > b	true
<	Less than	a < b	false
>=	Greater than or equal to	a >= b	true
<=	Less than or equal to	a <= b	false

🧠 Logical Operators

Operator	Description	Example	Result
&&	Logical AND	(a > 2 && b < 5)	true
||	Logical OR	(a > 10 || b < 5)	true
!	Logical NOT	!(a == b)	true

✅ if and else

Use if to test a condition. Use else to handle the opposite case.

void main() {
  int age = 20;

  if (age >= 18) {
    print("You are an adult.");
  } else {
    print("You are a minor.");
  }
}

📝 else if ladder

Use else if when you want to test multiple conditions.

void main() {
  int marks = 75;

  if (marks >= 90) {
    print("Grade: A+");
  } else if (marks >= 70) {
    print("Grade: B");
  } else {
    print("Grade: C");
  }
}

⚡ Ternary Operator

Shorthand for simple if-else.

void main() {
  int age = 17;
  String result = (age >= 18) ? "Adult" : "Minor";
  print(result);
}

🔀 switch-case Statement

Use switch when you have multiple fixed choices.

void main() {
  String day = "Tuesday";

  switch (day) {
    case "Monday":
      print("Start of the week");
      break;
    case "Tuesday":
      print("Second day");
      break;
    case "Friday":
      print("Almost weekend!");
      break;
    default:
      print("Normal day");
  }
}

🎯 Practice Assignments

1. Check if a number is even or odd.
2. Check if a number is positive, negative, or zero.
3. Take 3 subject marks and print the grade using if-else if.
4. Write a program using a ternary operator to check voter eligibility (age ≥ 18).
5. Write a calculator using switch for +, -, *, / operators.

🧪 Try these on DartPad.dev or your Dart console!