Truncate Two decimal places without rounding

c# math rounding
user147215 picture user147215 · Jun 29, 2010 · Viewed 178.6k times · Source

Lets say I have a value of 3.4679 and want 3.46, how can I truncate to two decimal places that without rounding up?

I have tried the following but all three give me 3.47:

void Main()
{
    Console.Write(Math.Round(3.4679, 2,MidpointRounding.ToEven));
    Console.Write(Math.Round(3.4679, 2,MidpointRounding.AwayFromZero));
    Console.Write(Math.Round(3.4679, 2));
}

This returns 3.46, but just seems dirty some how:

void Main()
{
    Console.Write(Math.Round(3.46799999999 -.005 , 2));
}

Answer

Hans Passant picture Hans Passant · Jun 29, 2010 
value = Math.Truncate(100 * value) / 100;

Beware that fractions like these cannot be accurately represented in floating point.

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