main.dart

// Import the 'dart:math' library to access mathematical functions.
import 'dart:math';

void main() {
  // ==================BASIC USAGE
  double height = 190.5; // Declare and initialize a double variable with a decimal value.
  double weight = 78.2;
  double temperature = 25.3;
  double? distance; // Nullable double variable.
  distance = 42.0;
  var someVariable = 72.5; // Dart infers the type as double.

  // =================ARITHMETIC OPERATIONS
  double x = 10.5;
  double y = 5.2;
  double sum = x + y; // Add two double values.
  double difference = x - y; // Subtract one double from another.
  double product = x * y; // Multiply two double values.
  double quotient = x / y; // Divide one double by another.

  // ==================PROPERTIES
  double number = 16.75;
  // 1. hashCode → int (Returns a hash code for a numerical value)
  number.hashCode; // (Not a property of double alone)
  // 2. isFinite → bool (Returns true if this double is finite; otherwise, returns false.)
  number.isFinite;
  // 3. isInfinite → bool (Returns true if this double is positive infinity or negative infinity; otherwise, returns false.)
  number.isInfinite;
  // 4. isNegative → bool (Returns true if this double is negative; otherwise, returns false.)
  number.isNegative;
  // 5. isNaN → bool (Returns true if this double is the special "not-a-number" (NaN) value; otherwise, returns false.)
  number.isNaN;
  // 6. sign → double (Returns -1.0 if the number is negative, 0.0 if it's zero, and 1.0 if it's positive.)
  number.sign;
  // 7. runtimeType → Type (A representation of the runtime type of the object.)
  number.runtimeType;

  // ================METHODS
  // 1. abs() → double (Returns the absolute value of this double)
  number.abs();
  // 2. ceil() → double (Returns the smallest integer value greater than or equal to this double.)
  number.ceil();
  // 3. floor() → double (Returns the largest integer value less than or equal to this double.)
  number.floor();
  // 4. truncate() → int (Returns the integer obtained by discarding any fractional part of this number)
  number.truncate();
  // 5. toStringAsFixed(int fractionDigits) → String (A decimal-point string-representation of this number)
  number.toStringAsFixed(2); //2 dp
  // 6. round() → int (Returns the integer value closest to this double.)
  number.round();
  // 7. toString() → String (Returns a string representation of this double.)
  number.toString();
  
  // ===============STATIC METHOD
  // 6. parse(String source) → double (Parse a string as a double literal and return its value.)
  String numString = "123.45";
  double parsedDouble = double.parse(numString);
  //print(parsedDouble);

  // 7. tryParse(String source) → double? (Parse a string as a double literal and return its value, or null if parsing fails.)
  String invalidString = "abc";
  double? parsedDoubleOrNull = double.tryParse(invalidString);
  //print(parsedDoubleOrNull); // This will print 'null' because parsing fails.
}