add /Operator_demo1.scala

README.md

@@ -216,6 +216,10 @@
 	```
 	- [SuperConstruct](./src/main/scala/ScalaBasic/SuperConstruct.scala), [SuperConstruct1 java](./src/main/scala/ScalaBasic/SuperConstruct1_java.java), [SuperConstruct2](./src/main/scala/ScalaBasic/SuperConstruct_2.scala), [SuperConstruct3](./src/main/scala/ScalaBasic/SuperConstruct_3.scala)- Scala/Java Super constructor examples
 
+	- Operator
+		- [Operator_demo1](./src/main/scala/ScalaBasic/Operator_demo1.scala)
+
+
 5. Scala class, trait, abstract class..
 	- Class
 		- Method create `class instance` in Scala

src/main/scala/ScalaBasic/Operator_demo1.scala

@@ -0,0 +1,63 @@
+package ScalaBasic
+
+// https://www.youtube.com/watch?v=oSq9JlaAelk&list=PLmOn9nNkQxJEqCNXBu5ozT_26xwvUbHyE&index=143
+
+object Operator_demo1 extends App {
+
+  // 1) if want to use "reserved" word, we need to add single comma : `xxx`
+  var `var` = 10
+  println ("var = " + `var`)
+
+  println("================")
+
+  // 2) "middle" operator
+  val n1 = 1
+  val n2 = 2
+  var r1 = n1 + n2
+  var r2 = n1.+(n2)  // n1 + n2
+
+  println("r1 = " + r1 + ",  r2 = " + r2)
+
+  println("================")
+
+  // 3) "middle" operator example
+  val dog = new Dog
+  println(dog.age)
+  dog.+(30)
+  println(dog.age)
+
+  dog + 30
+  println(dog.age)
+
+  println("================")
+
+  // 4) "post" operator example
+  val oper = new Operate
+  println(oper++)   // same as run def ++()
+  println(oper.++)  // same as run def ++()
+
+  println("================")
+
+  // 5) "pre" operator example
+  val oper2 = new Operate2
+  !oper2  //  def unary_!
+}
+
+
+class Dog { // "middle" operator example
+  var age:Int = 10
+  // let's define our "+" operator
+  def +(n:Int): Unit = {
+    age += n
+  }
+}
+
+class Operate { //  "post" operator example
+  // this method has no inout, so we can neglect the () here
+  def ++() = "123"
+}
+
+class Operate2 { // "pre" operator example
+  // this method has no inout, so we can neglect the () here
+  def unary_! = println("!!!!!!!!!!!")
+}