User Guide

72 Chapter 2: ActionScript Language Reference

+= (addition assignment)

Availability

Flash Player 4.

Usage

expression1 += expression2

Parameters

expression1,expression2

A number or string.

Returns

A string or a number.

Description

Operator (arithmetic compound assignment); assigns expression1 the value of expression1 +

expression2

. For example, the following two statements have the same result:

x += y;

x = x + y;

This operator also performs string concatenation. All the rules of the addition (+) operator apply

to the addition assignment

(+=) operator.

For more information, see “Operator precedence and associativity” in Using ActionScript in Flash.

Example

Usage 1: This example uses the += operator with a string expression and sends “My name is

Gilbert” to the Output panel.

var x1:String = "My name is ";

x1 += "Gilbert";

trace(x1); // output: My name is Gilbert

Usage 2: The following example shows a numeric use of the addition assignment (+=) operator:

var x:Number = 5;

var y:Number = 10;

x += y;

trace(x); // output: 15