Utility Function: RoundToClosest()
- March 22, 2010 10:04 PM
- ColdFusion, Utility Function
- Comments (0)
Its been a while! I got an email from a reader who wanted some help with a bit of image manipulation that has roused me back into CF coding! The particular bit of functionality he wants is rather complex, and so its been forcing me to make a bunch of utility functions to piece it together. First thing I ran into: rounding a number in CF is a little tricky. If you want to round to 2 decimal places, you should multiply the number by 100, call Round() and then divide by 100 again. What a waste. Luckily a little trickery with NumberFormat() can get us what we want.
<cfargument name="Value" type="numeric" required="true" />
<cfargument name="Places" type="numeric" required="false" default="0" />
<cfset var local = StructNew() />
<!--- Create the mask for NumberFormat --->
<cfset local.mask = "0" />
<!--- If we're doing decimals, format the mask correctly --->
<cfif arguments.Places gt 0>
<cfset local.mask = local.mask & "." & RepeatString("0", arguments.Places) />
</cfif>
<cfset local.returnValue = NumberFormat(arguments.Value, local.mask) />
<!--- Special Checks to prevent -0 oddity --->
<cfif local.returnValue eq "-0">
<cfset local.returnValue = 0 />
</cfif>
<cfreturn local.returnValue />
</cffunction>
The code is pretty straight forward; the only bit of weirdness is right at the end. When testing this function against some very-near-to-zero-negative-numbers, the function started to return weird results. In particular, with the value -.612342345e-16, the function returned "-0". Since 0 cannot be negative, I specifically check for this and set it back to 0. I'm not sure if "-0" could cause computational errors or not, but I'd prefer not to find out the hard way.
More to come!
