ActionScript for Flash MX: The Definitive Guide, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

120

|

Chapter 5: Operators

Modulo Division

The modulo operator performs so-called modulo division. It returns the remainder

(i.e., modulus) that results when the first operand is divided by the second. Modulo

division takes the general form:

operand1 % operand2

For example, 14%4returns the value 2 because 4 divides evenly into 14 three times,

with 2 being the remainder.

The operands of the modulo operator can be any valid numeric expression, includ-

ing integers and (unlike in C and C++) floating-point numbers. For example,

5%4is

1, and

5 % 4.5 is 0.5. If either operand is not of the number type, and conversion to a

number fails, the operation yields NaN.

If a number is even, the modulo will be zero when we divide the number by two. We

can use the trick shown in Example 5-1 to test whether a number is even or odd.

Unary Negation

The unary negation operator takes only one operand. It switches the operand’s sign

(i.e., positive becomes negative, and negative becomes positive). Unary negation

takes the general form:

–operand

The operand can be any valid expression. Here we test whether something’s horizon-

tal position is greater than the positive limit or less than the negative limit:

if (xPos > xBoundary || xPos < -xBoundary) {

// We've gone too far

}

The unary negation operator is simply a negative ...