Lesson 10: OR Operator - Intro to Kotlin

OR Operator Combine conditions with || (OR).

1fun main() {

2 val isTrue = true

3 val isFalse = false

4 if (isTrue || isFalse) {

5 println("at least one is true")

6 }

Terminal

$ kotlinc Main.kt -include-runtime -d Main.jar

$ java -jar Main.jar

at least one is true

Every line, explained

fun main() {: Every Kotlin program starts at the main function. When you run the program, Kotlin looks for fun main() and runs everything between its { and } from top to bottom.
val isTrue = true: A Boolean can store only one of two values: true or false, both lowercase.
val isFalse = false: A Boolean can store only one of two values: true or false, both lowercase.
if (isTrue || isFalse) {: if checks the condition inside its round brackets. If the condition is true, Kotlin runs the code between { and }. If it is false, Kotlin skips that code completely. || means OR: the whole condition is true if at least one side is true. true || false is true, so the block runs.
println("at least one is true"): println(...) prints whatever is inside the round brackets to the terminal, then moves to a new line. All lowercase, and no semicolon at the end; Kotlin does not need them.
}: This } closes the if block.
}: This closing curly brace } ends the main function. In Kotlin every opening brace { must have a matching closing brace }.