Flash CS3 Documentation

ActionScript 2.0 Language Reference > ActionScript language elements > Operators > -- decrement operator

-- decrement operator

--expression
expression--

A pre-decrement and post-decrement unary operator that subtracts 1 from the expression . The expression can be a variable, element in an array, or property of an object. The pre-decrement form of the operator (--expression) subtracts 1 from expression and returns the result. The post-decrement form of the operator (expression--) subtracts 1 from the expression and returns the initial value of expression (the value prior to the subtraction).

Availability: ActionScript 1.0; Flash Player 4

Operands

expression : Number - A number or a variable that evaluates to a number.

Returns

Number - The result of the decremented value.

Example

The pre-decrement form of the operator decrements x to 2 ( x - 1 = 2) and returns the result as y:

var x:Number = 3; 
var y:Number = --x; //y is equal to 2

The post-decrement form of the operator decrements x to 2 (x - 1 = 2 ) and returns the original value of x as the result y:

var x:Number = 3; 
var y:Number = x--; //y is equal to 3

The following example loops from 10 to 1, and each iteration of the loop decreases the counter variable i by 1.

for (var i = 10; i>0; i--) { 
 trace(i); 
}

Flash CS3