13.5 Increment and Decrement Operators

Another useful shortcut can be achieved using the Kotlin increment and decrement operators (also referred to as unary operators because they operate on a single operand). Consider the code fragment below:

x = x + 1 // Increase value of variable x by 1

x = x - 1 // Decrease value of variable x by 1

These expressions increment and decrement the value of x by 1. Instead of using this approach, however, it is quicker to use the ++ and -- operators. The following examples perform exactly the same tasks as the examples above:

x++ // Increment x by 1

x-- // Decrement x by 1

These operators can be placed either before or after the variable name. If the operator is placed before the variable name, the increment or decrement operation is performed before any other operations are performed on the variable. For example, in the following code, x is incremented before it is assigned to y, leaving y with a value of 10:

var x = 9

val y...