Expressions in Function. SHORT HAND SYNTAX

14_function_expressions.dart

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+
+// OBJECTIVE: Expression in Function: SHORT HAND SYNTAX
+
+void main() {
+
+	findPerimeter(4, 2);
+
+	int rectArea = getArea(10, 5);
+	print("The area is $rectArea");
+}
+
+void findPerimeter(int length, int breadth) => print("The perimeter is ${2 * (length + breadth)}");
+
+int getArea(int length, int breadth) => length * breadth;
+
+
+// "=>" is known as FAT ARROW
+// "=> expression" is a SHORT HAND SYNTAX for { return expression; }
+// Example "=> length * breadth" is SHORT HAND SYNTAX for { return length * breadth; }

15_optional_positional.dart

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+
+// 1. Required Parameters
+// 2. Optional Positional Parameters
+
+void main() {
+
+	printCities("New York", "New Delhi", "Sydney");
+	print("");
+
+	printCountries("USA");  // You can skip the Optional Positional Parameters
+
+}
+
+// Required Parameters
+void printCities(String name1, String name2, String name3) {
+
+	print("Name 1 is $name1");
+	print("Name 2 is $name2");
+	print("Name 3 is $name3");
+}
+
+// Optional Positional Parameters
+void printCountries(String name1, [String name2, String name3]) {
+
+	print("Name 1 is $name1");
+	print("Name 2 is $name2");
+	print("Name 3 is $name3");
+}

16_named_parameters.dart

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+
+// Optional Named Parameters
+
+void main() {
+	findVolume(10, breadth: 5, height: 20);
+	print("");
+
+	findVolume(10, height: 20, breadth: 5);     // Sequence doesn't matter in Named Parameter
+}
+
+
+int findVolume(int length, {int breadth, int height}) {
+
+	print("Length is $length");
+	print("Breadth is $breadth");
+	print("Height is $height");
+
+	print("Volume is ${length * breadth * height}");
+}

17_default_parameters.dart

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+
+// Optional Default Parameters
+
+void main() {
+
+	findVolume(10);     // Default value comes into action
+	print("");
+
+	findVolume(10, breadth: 5, height: 30);     // Overrides the old value with new one
+	print("");
+
+	findVolume(10, height: 30, breadth: 5);     // Making use of Named Parameters with Default values
+}
+
+
+int findVolume(int length, {int breadth = 2, int height = 20}) {
+
+	print("Lenght is $length");
+	print("Breadth is $breadth");
+	print("Height is $height");
+
+	print("Volume is ${length * breadth * height}");
+}