AdeCode

A year will be a leap year if it is divisible by 4 but not by 100. If a year is divisible by 4 and by 100, it is not a leap year unless it is also divisible by 400.

Translated into Actionscript 3.0, that looks like this:

function getIsLeapyear(year:int):Boolean{
	var result:Boolean = false;
	var divBy4:Boolean = (year % 4 == 0);
	var divBy100:Boolean = (year % 100 == 0);
	var divBy400:Boolean =  (year % 400 == 0);

	if(divBy4){
		if(divBy100){
			if(divBy400){
				result = true;
			} else {
				result = false;
			}
		} else {
			result = true;
		}
	} else {
		result = false;
	}
	return result;
}