DateDiff problem

[Guest]

This message is either a "FYI" or a way to embarass myself. I'm probably missing something very simple, or missing the point of the DateDiff function, so my apologies if this turns out to be a dumb posting.

I created a series of cfif/else statements to display a different text message depending on how many days remain in a survey. I used the DateDiff function. It works fine, counting down from 10 to zero days, but then it calculates the next instance as zero days again.

I solved my problem by switching to the DayOfYear function and that produces the correct result, but I'm perplexed why the DateDiff approach didn't work. Here's my DateDiff code:

<cfset CurrentYear = Year(Now())>
<cfset SVRSurveyEndDate = '4-20-#CurrentYear#'>
<cfset SVRSurveyDays = DATEDIFF('d',Now(),SVRSurveyEndDate + 1)>

If you change SVRSurveyEndDate one day at a time and output the result, you will see the results as +2, +1, 0, 0, -1 etc.

I solved my problem using this next line instead of the third line above:
<cfset SVRSurveyDays = (DayOfYear(SVRSurveyEndDate)) - (DayOfYear(Now())) + 1>

But I don't know why the DateDiff function produces the two zero results. I tried including hrs/min/sec in line 2 and varying the time, but that still produced two zero results.

[Dan_Bracuk]

Are you sure the final right bracket is in the right spot on this line?
<cfset SVRSurveyDays = DATEDIFF('d',Now(),SVRSurveyEndDate + 1)>

The reason you are getting zero twice is that you are comparing now(), which has a time component to other dates that don't.

[Newsgroup_User]

mikescott wrote:
> But I don't know why the DateDiff function produces the two zero results. I
> tried including hrs/min/sec in line 2 and varying the time, but that still
> produced two zero results.

w/out spending any time w/your logic, using day as the dateDiff datepart, you'll
always get an integer day rounded *down* ie 1.9999 days is 1 day as far as cf is
concerned:

<cfoutput>
#dateAdd("d",1.99999,now())#
</cfoutput>

produces a date only 1 day in the future.

[BKBK]

> But I don't know why the DateDiff function produces the two zero results.
A reason why