Logical Operators

Logical operators are used to combine multiple boolean expressions or invert a boolean value. They are critical for complex decision-making rules in control flow.

---

List of Logical Operators

Operator	Description	Logic
&&	Logical AND	Returns true if both expressions are true
||	Logical OR	Returns true if at least one expression is true
!	Logical NOT	Inverts the boolean value (unary operator)

---

Code Examples

1. Logical AND (&&)

dart
void main() {
  bool hasTicket = true;
  bool hasID = true;

  if (hasTicket && hasID) {
    print("Welcome to the flight!"); // Executed
  }
}

2. Logical OR (||)

dart
void main() {
  bool hasCash = false;
  bool hasCard = true;

  if (hasCash || hasCard) {
    print("Payment accepted!"); // Executed
  }
}

3. Logical NOT (!)

dart
void main() {
  bool isRaining = false;

  if (!isRaining) {
    print("Let's go for a walk!"); // Executed
  }
}

---

Short-Circuit Evaluation

Dart optimizes logical operations using short-circuit evaluation. This means the second operand is only evaluated if the first operand is not sufficient to determine the final result.

• For A && B: If A is false, the result is guaranteed to be false. Therefore, B is not evaluated.
• For A || B: If A is true, the result is guaranteed to be true. Therefore, B is not evaluated.

dart
bool checkHeavyCondition() {
  print("Running heavy check...");
  return true;
}

void main() {
  bool isFastCheckFailed = false;

  // Short-circuit prevents checkHeavyCondition() from running
  if (isFastCheckFailed && checkHeavyCondition()) {
    print("Inside");
  }
  print("Done"); // Prints only "Done"
}

---

Summary

• Use && (AND) when all conditions must be met.
• Use || (OR) when at least one condition must be met.
• Use ! (NOT) to reverse a boolean value.
• Short-circuiting saves compute time by avoiding unnecessary evaluation of secondary expressions.