Question

I have a double typed variable. This variable stores information that is part of a more complex formula. Importantly, this variable can only include information up to the tenths location, or one decimal position (i.e. 10.1, 100.2, etc). However, when determining this value, it must be calculated such that anything past the tenths location is truncated, not rounded. For instance:

if the value equals 10.44, The variable value should be 10.4.
if the value equals 10.45, The variable value should also be set to 10.4

How do I truncate values in C# with respect to a decimal place?

Answer 1

Using an extension method:

public static double RoundDown(this double value, int digits)
{
     int factor = Math.Pow(10,digits);

     return Math.Truncate(value * factor) / factor;
}

Then you simply use it like this:

double rounded = number.RoundDown(2);