Question

I am running a LINQ query that is using local “let” variables to calculate a local value to compare against a parameter that is passed into the query.

I have the following query:

Items = from lead in Items
        let total = lead.NurtureActions.Count(q => !q.Deleted)
        let completed = lead.NurtureActions.Count(nurtureAction => nurtureAction.Completed && !nurtureAction.Deleted)
        let percentage = Math.Round((Double)((completed/total)*100),0,MidpointRounding.ToEven)
        where 
            total>0 && 
            percentage == progress
        select lead;

The part that is really important above is the following line:

let percentage = Math.Round((Double)((completed/total)*100),0,MidpointRounding.ToEven)

As you can see in my query, I am comparing the result of that query with progress, which is passed into my function.

For example: I might pass in the value 8, so progress will have the value 8. But the calculated percentage might initially be 8.223, but I need that to round to 8.

I believed that I was doing this correctly, but for some reason, something is not working correctly.

Any ideas of what might be throwing the rounding off? I have also tried the AwayFromZero option for rounding, but that doesn’t work either.

Edit For those who requested more information, I am not sure what value it is calculating. I am not experienced with debugging LINQ queries, and wouldn’t know where to begin to find out what that value is. I would provide it if I knew how to get it.

Answer 1

Random guess: total and completed are ints, so (completed/total) results in a truncated value. The truncated value is multiplied by 100 and then converted to double.

I guess this produces unexpected results in some cases if you expect that (completed/total) returns a double.

Fix:

let total = (double)lead.NurtureActions.Count(...)
let completed = (double)lead.NurtureActions.Count(...)
let percentage = Math.Round((completed/total)*100, ...)