Dart Advanced Lesson 104 of 107 8 min read

Dart Programming Examples: 30 Simple Programs with Output

30 easy Dart programming examples for beginners with code and output: hello world, even odd, factorial, Fibonacci, prime numbers, palindrome, classes, async and more.

On this page

These are the small programs every beginner writes, solved in clear, modern Dart. Each one shows the code and the output. Press Run to try it in the browser, then change it: use other numbers, add a feature, break it on purpose and read the error. That is the fastest way to learn Dart.

The examples go from very easy to intermediate. If a keyword is new to you, follow the link under the example to the lesson that explains it.

Basics

1. Hello, World

void main() {
  print('Hello, World!');
}

Hello, World!

Explained in Your first Dart program.

2. Add two numbers

void main() {
  int a = 12;
  int b = 30;
  print('Sum: ${a + b}');
}

Sum: 42

3. Even or odd

void main() {
  for (var n in [7, 10]) {
    print('$n is ${n.isEven ? 'even' : 'odd'}');
  }
}

7 is odd
10 is even

Uses the ternary operator.

4. Largest of three numbers

import 'dart:math';

void main() {
  var a = 14, b = 27, c = 9;

  var largest = a;
  if (b > largest) largest = b;
  if (c > largest) largest = c;
  print('Largest: $largest');

  // The same thing in one line:
  print('Largest: ${[a, b, c].reduce(max)}');
}

Largest: 27
Largest: 27

5. Simple calculator

double calculate(double a, String op, double b) => switch (op) {
      '+' => a + b,
      '-' => a - b,
      '*' => a * b,
      '/' => a / b,
      _ => throw ArgumentError('Unknown operator $op'),
    };

void main() {
  for (var op in ['+', '-', '*', '/']) {
    print('8 $op 2 = ${calculate(8, op, 2)}');
  }
}

8 + 2 = 10.0
8 - 2 = 6.0
8 * 2 = 16.0
8 / 2 = 4.0

Uses a switch expression.

6. Temperature converter

void main() {
  var celsius = 25;
  var fahrenheit = celsius * 9 / 5 + 32;
  print('$celsius°C = ${fahrenheit.toStringAsFixed(1)}°F');

  var bodyTemp = 98.6;
  var inCelsius = (bodyTemp - 32) * 5 / 9;
  print('$bodyTemp°F = ${inCelsius.toStringAsFixed(1)}°C');
}

25°C = 77.0°F
98.6°F = 37.0°C

7. Simple interest

void main() {
  var principal = 10000;
  var rate = 5;  // percent per year
  var years = 3;

  var interest = principal * rate * years / 100;
  print('Interest: $interest');
  print('Total: ${principal + interest}');
}

Interest: 1500.0
Total: 11500.0

8. Leap year

bool isLeapYear(int year) =>
    (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;

void main() {
  for (var year in [1900, 2000, 2024, 2026]) {
    print('$year: ${isLeapYear(year)}');
  }
}

1900: false
2000: true
2024: true
2026: false

9. Grade from marks

String grade(int score) => switch (score) {
      >= 90 => 'A',
      >= 75 => 'B',
      >= 50 => 'C',
      _ => 'F',
    };

void main() {
  for (var score in [95, 80, 62, 30]) {
    print('$score: ${grade(score)}');
  }
}

95: A
80: B
62: C
30: F

>= 90 inside a switch is a relational pattern.

Loops

10. Multiplication table

void main() {
  var n = 5;
  for (var i = 1; i <= 10; i++) {
    print('$n x $i = ${n * i}');
  }
}

5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50

11. Sum of 1 to 100

void main() {
  var sum = 0;
  for (var i = 1; i <= 100; i++) {
    sum += i;
  }
  print('Sum: $sum');
}

Sum: 5050

See Loops in Dart.

12. FizzBuzz

void main() {
  var out = List.generate(15, (index) {
    var i = index + 1;
    if (i % 15 == 0) return 'FizzBuzz';
    if (i % 3 == 0) return 'Fizz';
    if (i % 5 == 0) return 'Buzz';
    return '$i';
  });
  print(out.join(' '));
}

1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz

13. Star pyramid

void main() {
  var rows = 4;
  for (var i = 1; i <= rows; i++) {
    print(' ' * (rows - i) + '*' * (2 * i - 1));
  }
}

   *
  ***
 *****
*******

14. Factorial

int factorial(int n) => n <= 1 ? 1 : n * factorial(n - 1);

void main() {
  print('5! = ${factorial(5)}');
  print('10! = ${factorial(10)}');
}

5! = 120
10! = 3628800

A function that calls itself is called recursion.

15. Fibonacci series

void main() {
  var fib = [0, 1];
  while (fib.length < 10) {
    fib.add(fib[fib.length - 1] + fib[fib.length - 2]);
  }
  print(fib.join(', '));
}

0, 1, 1, 2, 3, 5, 8, 13, 21, 34

16. Prime numbers

bool isPrime(int n) {
  if (n < 2) return false;
  for (var i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return true;
}

void main() {
  var primes = List.generate(30, (i) => i + 1).where(isPrime).toList();
  print(primes);
}

[2, 3, 5, 7, 11, 13, 17, 19, 23, 29]

Strings

17. Reverse a string

void main() {
  var word = 'Flutter';
  var reversed = word.split('').reversed.join();
  print(reversed);
}

rettulF

18. Palindrome check

bool isPalindrome(String s) {
  var clean = s.toLowerCase();
  return clean == clean.split('').reversed.join();
}

void main() {
  for (var word in ['level', 'dart', 'Racecar']) {
    print('$word: ${isPalindrome(word)}');
  }
}

level: true
dart: false
Racecar: true

19. Count vowels

void main() {
  var text = 'Learn Dart programming';
  var count = text
      .toLowerCase()
      .split('')
      .where((c) => 'aeiou'.contains(c))
      .length;
  print('Vowels: $count');
}

Vowels: 6

More tools in Dart string methods.

20. Word frequency

void main() {
  var sentence = 'dart is fun and dart is fast';
  var counts = <String, int>{};

  for (var word in sentence.split(' ')) {
    counts[word] = (counts[word] ?? 0) + 1;
  }
  print(counts);
}

{dart: 2, is: 2, fun: 1, and: 1, fast: 1}

Uses a Map.

Lists

21. Average, highest and lowest

void main() {
  var marks = [72, 45, 91, 38, 84];

  var total = marks.fold(0, (sum, m) => sum + m);
  var highest = marks.reduce((a, b) => a > b ? a : b);
  var lowest = marks.reduce((a, b) => a < b ? a : b);

  print('Average: ${(total / marks.length).toStringAsFixed(1)}');
  print('Highest: $highest');
  print('Lowest: $lowest');
}

Average: 66.0
Highest: 91
Lowest: 38

22. Remove duplicates

void main() {
  var numbers = [3, 1, 3, 2, 1];
  print(numbers.toSet().toList());
}

[3, 1, 2]

23. Sort names alphabetically

void main() {
  var names = ['Sita', 'Arjun', 'Maya', 'Bikash'];
  names.sort();
  print(names);
}

[Arjun, Bikash, Maya, Sita]

Every list tool is in Dart list methods.

Functions, classes and null safety

24. Return two values with a record

(int, int) minMax(List<int> numbers) {
  var sorted = [...numbers]..sort();
  return (sorted.first, sorted.last);
}

void main() {
  final (lowest, highest) = minMax([4, 9, 1, 7]);
  print('min $lowest, max $highest');
}

min 1, max 9

See Records in Dart.

25. Handle a missing value (null safety)

String? findUser(int id) => id == 1 ? 'Asha' : null;

void main() {
  print(findUser(1) ?? 'Guest');
  print(findUser(2) ?? 'Guest');
  print(findUser(2)?.length);
}

Asha
Guest
null

See Null-aware operators.

26. Bank account class

class BankAccount {
  final String owner;
  double _balance = 0;

  BankAccount(this.owner);

  double get balance => _balance;

  void deposit(double amount) {
    if (amount <= 0) throw ArgumentError('Deposit must be positive');
    _balance += amount;
  }

  void withdraw(double amount) {
    if (amount > _balance) throw StateError('Insufficient funds');
    _balance -= amount;
  }
}

void main() {
  var account = BankAccount('Asha');
  account.deposit(500);
  account.withdraw(120);
  print('${account.owner}: ${account.balance}');

  try {
    account.withdraw(1000);
  } on StateError catch (e) {
    print('Error: ${e.message}');
  }
}

Asha: 380.0
Error: Insufficient funds

See Classes and objects and Exception handling.

27. Shapes with inheritance and polymorphism

import 'dart:math';

abstract class Shape {
  String get name;
  double get area;
}

class Circle extends Shape {
  final double radius;
  Circle(this.radius);

  @override
  String get name => 'Circle';
  @override
  double get area => pi * radius * radius;
}

class Rectangle extends Shape {
  final double width, height;
  Rectangle(this.width, this.height);

  @override
  String get name => 'Rectangle';
  @override
  double get area => width * height;
}

void main() {
  List<Shape> shapes = [Circle(2), Rectangle(3, 4)];
  for (var shape in shapes) {
    print('${shape.name}: ${shape.area.toStringAsFixed(2)}');
  }
}

Circle: 12.57
Rectangle: 12.00

See Abstract classes and Polymorphism.

Async, streams and JSON

28. Wait for a result with async and await

Future<String> fetchGreeting() async {
  await Future.delayed(const Duration(seconds: 1)); // pretend to call a server
  return 'Hello from the server';
}

void main() async {
  print('Fetching...');
  var message = await fetchGreeting();
  print(message);
}

Fetching...
Hello from the server

See async and await in Dart.

29. Countdown with a stream

Stream<int> countdown(int from) async* {
  for (var i = from; i > 0; i--) {
    await Future.delayed(const Duration(milliseconds: 500));
    yield i;
  }
}

void main() async {
  await for (var n in countdown(3)) {
    print(n);
  }
  print('Lift off!');
}

3
2
1
Lift off!

See Streams in Dart and Generators.

30. Read and write JSON

import 'dart:convert';

void main() {
  var text = '{"name": "Dart", "year": 2011}';
  var data = jsonDecode(text) as Map<String, dynamic>;
  print('${data['name']} was first announced in ${data['year']}');

  var output = jsonEncode({'language': 'Dart', 'fast': true});
  print(output);
}

Dart was first announced in 2011
{"language":"Dart","fast":true}

See Working with JSON in Dart.

What to do next

Solve each example a second way. For example, write factorial with a loop, or FizzBuzz with a switch.
Move on to bigger Dart practice projects.
Test yourself with Dart interview questions.
Ready for apps? Try the Flutter examples.

Try it yourself

Pick three examples from this page and extend them: make the multiplication table print any number from 1 to 12, make the calculator handle %, and make the word counter ignore capital letters and punctuation.