Dart Booleans

Working with true and false values

✅ What are Dart Booleans?

Booleans in Dart represent logical values that can only be true or false. They are essential for decision-making, conditions, and controlling program flow in your applications. 


// Boolean examples
bool isActive = true;
bool isComplete = false;
print(isActive); // Output: true

Boolean Basics

✅

True Value

Represents a positive condition 

bool isReady = true;
❌

False Value

Represents a negative condition 

bool isFinished = false;
🔄

Comparisons

Result from comparing values 

bool result = 5 > 3; // true
🎯

Conditions

Used in if statements and loops 

if (isReady) {
  print('Go!');
}

🔹 Boolean Declaration

Different ways to create and use boolean variables: 

// Direct assignment
bool isLoggedIn = true;
bool hasPermission = false;

// From comparisons
bool isAdult = age >= 18;
bool isEqual = name == 'John';

// From method calls
bool isEmpty = text.isEmpty;
bool contains = list.contains(item);

print('Logged in: $isLoggedIn');
print('Has permission: $hasPermission');
print('Is adult: $isAdult');

Output:

Logged in: true
Has permission: false
Is adult: true

🔹 Boolean Operators

Logical operators to combine and manipulate boolean values: 

bool a = true;
bool b = false;

// AND operator (&&)
bool andResult = a && b;
print('$a && $b = $andResult'); // Output: true && false = false

// OR operator (||)
bool orResult = a || b;
print('$a || $b = $orResult'); // Output: true || false = true

// NOT operator (!)
bool notA = !a;
bool notB = !b;
print('!$a = $notA'); // Output: !true = false
print('!$b = $notB'); // Output: !false = true

Output:

true && false = false
true || false = true
!true = false
!false = true

🔹 Boolean in Conditions

Using booleans to control program flow: 

bool isWeekend = true;
bool isRaining = false;
int temperature = 25;

// Simple if condition
if (isWeekend) {
  print('Time to relax!');
}

// Complex conditions
if (isWeekend && !isRaining && temperature > 20) {
  print('Perfect day for a picnic!');
} else if (isWeekend && isRaining) {
  print('Good day to stay inside and read.');
} else {
  print('Regular day, time to work!');
}

// Ternary operator
String activity = isWeekend ? 'Relax' : 'Work';
print('Today\'s activity: $activity');

Output:

Time to relax!
Perfect day for a picnic!
Today's activity: Relax

🔹 Boolean Methods

Common methods that return boolean values: 

String text = 'Hello Dart';
List<int> numbers = [1, 2, 3, 4, 5];

// String methods returning bool
print(text.isEmpty); // Output: false
print(text.isNotEmpty); // Output: true
print(text.contains('Dart')); // Output: true
print(text.startsWith('Hello')); // Output: true
print(text.endsWith('Java')); // Output: false

// List methods returning bool
print(numbers.isEmpty); // Output: false
print(numbers.isNotEmpty); // Output: true
print(numbers.contains(3)); // Output: true

// Number comparisons
int age = 25;
print(age.isEven); // Output: false
print(age.isOdd); // Output: true

Output:

false
true
true
true
false
false
true
true
false
true

🧠 Test Your Knowledge

What is the result of: true && false?