Checking a date is between two dates - coldfusion

Question

In ColdFusion I can see the code below, however it does not seem to work. I want to make sure discount is only applied if the valid from and to dates are in range, see below.
if (
DATEDIFF("d", discount.ValidFrom(), now()) >= 0
AND
DATEDIFF("d", now(), discount.ValidTo()) <= 0
){
// ALL OK Accept Discount
}
else
{
// Discount is no Longer Valid boo!
}

Answer 1

Try this:
Today = Int(Now());
if ( Today GTE Int(discount.ValidFrom())
AND Today LTE Int(discount.ValidTo())
)
{
// discount is valid
}
else
{
// no longer valid
}
It works because datetimes are basically just numbers - with the integer/whole part being the days and the decimal/fraction part being the time.
So applying the Int function will convert a datetime to a whole day date, and then you can just do a simple numeric comparison to ensure it is within the ranges.
I find this far more readable and understandable than the DateDiff stuff - there's no confusion over the ordering of things, which I think is the problem with your provided code snippet (you've switched both order and lte/gte; you only wanted to change one or the other).

Answer 2

Your logic is a bit off. Right now you're returning
if ({positive_number} and {negative_number})
which returns false. You should be checking if dateDiff("d", today, discount.to()) is also >= 0.
<cfscript>
local = {};
local.start = createDate( 2011, 10, 01 );
local.end = createDate( 2011, 10, 30 );
local.today = now();
local.valid = false;
if ( (dateDiff("d", local.start, local.today) >= 0)
AND (dateDiff("d", local.today, local.end) >= 0) ){
local.valid = true;
}
</cfscript>
<cfoutput>
x < z: #dateDiff("d", local.start, local.today) GTE 0#
<hr />
z < y: #dateDiff("d", local.today, local.end) GTE 0#
<hr />
Valid: #local.valid#
</cfoutput>