6. Dart Data Types

Dart supports various data types, allowing you to store and manipulate different kinds of data. Here’s a concise overview of the basic data types in Dart with examples:

 1. Numbers

Dart has two types of numbers: `int` for integer values and `double` for floating-point values.

void main() {
  int age = 25;
  double height = 5.9;
  
  print('Age: $age, Height: $height');
}

2. Strings

Strings represent a sequence of characters.

void main() {
  String greeting = 'Hello, Dart!';
  String name = 'Alice';
  
  print('$greeting My name is $name.');
}

3. Booleans

Booleans represent true or false values.

void main() {
  bool isDartFun = true;
  bool isSnowing = false;
  
  print('Is Dart fun? $isDartFun');
  print('Is it snowing? $isSnowing');
}

4. Lists

Lists are ordered collections of items.

void main() {
  List<int> numbers = [1, 2, 3, 4, 5];
  List<String> fruits = ['Apple', 'Banana', 'Cherry'];
  
  print('Numbers: $numbers');
  print('Fruits: $fruits');
}

5. Sets

Sets are collections of unique items.

void main() {
  Set<int> uniqueNumbers = {1, 2, 3, 3, 4};
  Set<String> uniqueFruits = {'Apple', 'Banana', 'Cherry', 'Apple'};
  
  print('Unique Numbers: $uniqueNumbers'); // {1, 2, 3, 4}
  print('Unique Fruits: $uniqueFruits'); // {Apple, Banana, Cherry}
}

Difference between List and Sets

List

• Ordered: Elements in a List are ordered. This means each element has an index and can be accessed by its position.
• Duplicates: A List can contain duplicate elements.

Set

• Unordered: Elements in a Set are unordered. There is no index, and elements cannot be accessed by position.

Unique Elements: A Set cannot contain duplicate elements. Each element is unique.

void main() {
  // Using List to keep track of enrollment order
  List<String> studentEnrollmentOrder = [];
  studentEnrollmentOrder.add("Alice");
  studentEnrollmentOrder.add("Bob");
  studentEnrollmentOrder.add("Alice"); // Duplicate allowed
  studentEnrollmentOrder.add("Charlie");

  // Print student enrollment order
  print("Student Enrollment Order:");
  for (var student in studentEnrollmentOrder) {
    print(student);
  }

  // Using Set to keep track of unique event registrants
  Set<String> eventRegistrants = {};
  eventRegistrants.add("Alice");
  eventRegistrants.add("Bob");
  eventRegistrants.add("Alice"); // Duplicate not allowed, will be ignored
  eventRegistrants.add("Charlie");

  // Print unique event registrants
  print("\nUnique Event Registrants:");
  for (var registrant in eventRegistrants) {
    print(registrant);
  }
}

6. Maps

Maps are collections of key-value pairs.

void main() {
  Map<String, int> scores = {
    'Alice': 90,
    'Bob': 85,
    'Charlie': 95
  };
  
  print('Scores: $scores');
  print('Alice\'s score: ${scores['Alice']}');
}
```

7. Runes

Runes represent Unicode characters.

void main() {
  String heart = '\u2665'; // Unicode for heart symbol
  
  print('Heart: $heart');
}

8. Symbols

Reflective programming, also known as reflection, is a programming technique where a program can inspect and modify its own structure and behavior at runtime

Symbols are used to refer to identifiers by name, primarily in reflection.

void main() {
  Symbol libraryName = #dart.core;
  
  print('Library Symbol: $libraryName');
}

9. Null Safety

By default, variables cannot be null unless specified with `?`.

void main() {
  int? nullableInt = null;
  String? nullableString = null;
  
  print('Nullable int: $nullableInt');
  print('Nullable string: $nullableString');
}

These data types cover most of the basic needs for storing and manipulating data in Dart programs.