Trying to replace Double value in list

Question

Could someone please help me with this. I'm trying to replace the Value with the same value but only with the first decimal. As you can see below i end up with the same result as I start with.

public class QoutaDataHolder
{
  public double StartTime { get; set; }

  public double EndTime { get; set; }

  public double Value { get; set; }

  public string QoutaRuleID { get; set; }
}

List<QoutaDataHolder> correctionQoutas

for (int i = 0; i < correctionQoutas.Count; i++)
{
  if (correctionQoutas[i].Value % 1 != 0) //Value = 2.88888889
  {
    var trunkatedValue = Math.Truncate(correctionQoutas[i].Value*10); //28
    double newValue = trunkatedValue/10; // Back to 2.88888889!?!?
    correctionQoutas[i].Value = newValue; // Want to assign 2.8
  }
}

EDIT: I don't want to round the value!

I always want the first decimal, undependant of what the second decimal is. — Andy, May 10 '16 at 12:16
[http://stackoverflow.com/questions/2453951/c-sharp-double-tostring-formatting-with-two-decimal-places-but-no-rounding](http://stackoverflow.com/questions/2453951/c-sharp-double-tostring-formatting-with-two-decimal-places-but-no-rounding) — Jason Evans, May 10 '16 at 12:18
I'm not sure floating point numbers are a good fit if the exact decimal fraction is important (e.g. this is money). You should probably consider using `decimal` instead - see [this question](http://stackoverflow.com/questions/1165761/decimal-vs-double-which-one-should-i-use-and-when) — Charles Mager, May 10 '16 at 12:22

score 0 · Answer 1 · answered May 10 '16 at 12:17

Ehsan Sajjad is right. You need to use Math.Round with second parameter as 1.

for (int i = 0; i < correctionQoutas.Count; i++)
{
  if (correctionQoutas[i].Value % 1 != 0) //Value = 2.88888889
  {
    correctionQoutas[i].Value = math.Round(correctionQoutas[i].Value, 1); // Want to assign 2.8
  }
}

score 0 · Accepted Answer · answered May 10 '16 at 12:21

Here is a solution specific to your question: Just use conversions to get the values

for (int i = 0; i < correctionQoutas.Count; i++)
{
    if (correctionQoutas[i].Value % 1 != 0) //Value = 2.88888889
    {
        var trunkatedValue = (int)(correctionQoutas[i].Value * 10); //28
        double newValue = (double)trunkatedValue / 10; // not back to 2.88888889 anymore
        correctionQoutas[i].Value = newValue;
    }
}

score -1 · Answer 3 · answered May 10 '16 at 12:19

-1

You could do:

var trunkatedValue = Math.Floor(correctionQoutas[i].Value*10); //28

answered May 10 '16 at 12:19

Jonathan Nappee

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Trying to replace Double value in list

3 Answers3