functions

Rajeev Kumar Singh · Rajeev Kumar Singh · commit 36f133a3fb9a · 2018-01-19T23:16:19.000+05:30
diff --git a/src/t9_functions/DefaultArguments.kt b/src/t9_functions/DefaultArguments.kt
@@ -0,0 +1,18 @@
+package t9_functions
+
+// Function with Default Argument
+fun displayGreeting(message: String, name: String = "Guest") {
+    println("Hello $name, $message")
+}
+
+// Function with a default parameter preceding a non-default parameter
+fun arithmeticSeriesSum(a: Int = 1, n: Int, d: Int = 1): Int {
+    return n/2 * (2*a + (n-1)*d)
+}
+
+fun main(args: Array<String>) {
+    displayGreeting("Welcome to the CalliCoder Blog", "John")
+    displayGreeting("Welcome to the CalliCoder Blog")
+
+    arithmeticSeriesSum(1, 10)
+}
diff --git a/src/t9_functions/Functions.kt b/src/t9_functions/Functions.kt
@@ -0,0 +1,21 @@
+package t9_functions
+
+// Function
+fun avg(a: Double, b: Double): Double {
+    return  (a + b)/2
+}
+
+// Single Expression Function
+fun avgSingleExpression(a: Double, b: Double) = (a + b)/2
+
+
+// Unit returning Function
+fun printAverage(a: Double, b: Double): Unit {
+    println("Avg of ($a, $b) = ${(a + b)/2}")
+}
+
+fun main(args: Array<String>) {
+    println(avg(4.6, 9.0))
+    println(avgSingleExpression(4.6, 9.0))
+    printAverage(4.6, 9.0);
+}
diff --git a/src/t9_functions/InfixNotation.kt b/src/t9_functions/InfixNotation.kt
@@ -0,0 +1,21 @@
+package t9_functions
+
+data class ComplexNumber(val realPart: Double, val imaginaryPart: Double) {
+    // Infix function for adding two complex numbers
+    infix fun add(c: ComplexNumber): ComplexNumber {
+        return ComplexNumber(realPart + c.realPart, imaginaryPart + c.imaginaryPart)
+    }
+}
+
+fun main(args: Array<String>) {
+    // Infix function example
+
+    val c1 = ComplexNumber(3.0, 5.0)
+    val c2 = ComplexNumber(4.0, 7.0)
+
+    // Usual call
+    c1.add(c2) // produces - ComplexNumber(realPart=7.0, imaginaryPart=12.0)
+
+    // Infix call
+    c1 add c2  // produces - ComplexNumber(realPart=7.0, imaginaryPart=12.0)
+}
diff --git a/src/t9_functions/LocalFunctions.kt b/src/t9_functions/LocalFunctions.kt
@@ -0,0 +1,23 @@
+package t9_functions
+
+// Local/Nested Function
+fun findBodyMassIndex(weightInKg: Double, heightInCm: Double): Double {
+    if(weightInKg <= 0) {
+        throw IllegalArgumentException("Weight must be greater than zero")
+    }
+    if(heightInCm <= 0) {
+        throw IllegalArgumentException("Height must be greater than zero")
+    }
+
+    // Nested function has access to the local variables of the outer function
+    fun calculateBMI(): Double {
+        val heightInMeter = heightInCm / 100
+        return weightInKg / (heightInMeter * heightInMeter)
+    }
+
+    return calculateBMI()
+}
+
+fun main(args: Array<String>) {
+    println(findBodyMassIndex(68.5, 170.0))
+}
diff --git a/src/t9_functions/NamedArguments.kt b/src/t9_functions/NamedArguments.kt
@@ -0,0 +1,14 @@
+package t9_functions
+
+fun main(args: Array<String>) {
+    // Function call with Named Arguments
+    arithmeticSeriesSum(n=10)
+    arithmeticSeriesSum(a=3, n=10, d=2)
+
+    // You can also reorder the arguments if you’re specifying the names
+    arithmeticSeriesSum(n=10, d=2, a=3)
+
+    // You can use a mix of named arguments and position-based arguments
+    // as long as all the position-based arguments are placed before the named arguments
+    arithmeticSeriesSum(3, n=10)
+}
diff --git a/src/t9_functions/Varargs.kt b/src/t9_functions/Varargs.kt
@@ -0,0 +1,39 @@
+package t9_functions
+
+// Vararg function
+fun sumOfNumbers(vararg numbers: Double): Double {
+    var sum: Double = 0.0
+    for(number in numbers) {
+        sum += number
+    }
+    return sum
+}
+
+// Vararg function with another parameter
+fun sumOfNumbers(vararg numbers: Double, initialSum: Double): Double {
+    var sum = initialSum
+    for(number in numbers) {
+        sum += number
+    }
+    return sum
+}
+
+fun main(args: Array<String>) {
+    // Calling vararg function
+
+    sumOfNumbers(1.5, 2.0)  // Result = 3.5
+
+    sumOfNumbers(1.5, 2.0, 3.5, 4.0, 5.8, 6.2)  // Result = 23.0
+
+    sumOfNumbers(1.5, 2.0, 3.5, 4.0, 5.8, 6.2, 8.1, 12.4, 16.5)  // Result = 60.0
+
+
+    // If there are other parameters following the vararg parameter,
+    // then the values for those parameters can be passed using the named argument syntax -
+    sumOfNumbers(1.5, 2.5, initialSum=100.0)
+
+
+    // Pass an array to the vararg function using spread operator
+    val a = doubleArrayOf(1.5, 2.6, 5.4)
+    sumOfNumbers(*a)  // Result = 9.5
+}
