Logical Operators

Overview

Logical operators are used to combine or invert boolean values. They are essential for creating complex conditions in your programs.

Logical Operators Table

Operator	Name	Description	Example
`&&`	AND	Returns `true` if both operands are true	`true && false` → `false`
`		`	OR	Returns `true` if at least one operand is true	`true	false`→`true`
`!`	NOT	Inverts the boolean value	`!true` → `false`

Basic Example

Here’s a complete example demonstrating logical operators:

void main() {
  bool esEstudiante = true;
  bool tieneTitulo = false;
  int valor = 28;

  print(valor == 18 || tieneTitulo);
  print(esEstudiante && tieneTitulo);  // AND: false
  //print(esEstudiante || tieneTitulo);  // OR: true
  print(!esEstudiante);                // NOT: false

  /*
  Tabla de verdad AND:
  true  && true   = true
  true  && false  = false
  false && true   = false
  false && false  = false
  */
}

Output:

false
false
false

AND Operator (`&&`)

The AND operator returns true only when both conditions are true.

Truth Table for AND

Left	Right	Result
`true`	`true`	`true`
`true`	`false`	`false`
`false`	`true`	`false`
`false`	`false`	`false`

Example

bool hasLicense = true;
bool hasInsurance = true;
bool canDrive = hasLicense && hasInsurance;
print(canDrive);  // Output: true

The AND operator uses “short-circuit” evaluation: if the left operand is false, the right operand is not evaluated because the result will always be false.

OR Operator (`||`)

The OR operator returns true when at least one condition is true.

Truth Table for OR

Left	Right	Result
`true`	`true`	`true`
`true`	`false`	`true`
`false`	`true`	`true`
`false`	`false`	`false`

Example

bool isWeekend = false;
bool isHoliday = true;
bool canRelax = isWeekend || isHoliday;
print(canRelax);  // Output: true

The OR operator also uses “short-circuit” evaluation: if the left operand is true, the right operand is not evaluated because the result will always be true.

NOT Operator (`!`)

The NOT operator inverts a boolean value.

Truth Table for NOT

Value	Result
`true`	`false`
`false`	`true`

Example

bool isLoggedIn = true;
bool isGuest = !isLoggedIn;
print(isGuest);  // Output: false

The NOT operator is useful for checking the opposite of a condition. For example, !isEmpty is more readable than isEmpty == false.

Combining Logical Operators

You can combine multiple logical operators to create complex conditions:

int age = 25;
bool hasTicket = true;
bool isStudent = false;

// Must be 18 or older AND have a ticket OR be a student
bool canEnter = (age >= 18 && hasTicket) || isStudent;
print(canEnter);  // Output: true

Practical Examples

Access Control

bool isAdmin = false;
bool isOwner = true;
bool canDelete = isAdmin || isOwner;
print(canDelete);  // Output: true

Form Validation

String username = "john";
String password = "pass1234";

bool validUsername = username.length >= 3;
bool validPassword = password.length >= 8;
bool canSubmit = validUsername && validPassword;

print(canSubmit);  // Output: true

Eligibility Check

int age = 16;
bool hasParentalConsent = true;

bool canParticipate = age >= 18 || (age >= 13 && hasParentalConsent);
print(canParticipate);  // Output: true

Inverted Conditions

bool isProcessing = false;
bool canStart = !isProcessing;
print(canStart);  // Output: true

Getting Started

Fundamentals

Operators

Control Flow

Functions

Data Structures

Input & Output

Practical Exercises

Overview