Format currency without rounding

Question

I have the need to format a decimal number as currency but I do not wish for any rounding to occur in the process.

For example (example culture is en-US)

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Answer 1

You could do something like this...

var money = 1234.556789D;
Console.WriteLine(money.ToString(GetFormat(money)));

money = .1D;

Console.WriteLine(money.ToString(GetFormat(money)));

using the following method to get the format string...

static string GetFormat(double input)
{
    // get the number of decimal places to show
    int length = input.ToString().Length - input.ToString().IndexOf(".") - 1;

    // return the currency format string to use with decimal.ToString()
    return string.Format("C{0}", length < 2 ? 2 : length);
}

If you wanted to take it a step further, you could also wrap all of this into an extension method so that you didn't have to call the GetFormat() method from inside ToString() - that might make things look a bit cleaner.