从双精度转换为十进制时避免溢出异常

Question

When converting double (or float ) to decimal , overflow exceptions are possible. So I've written this small extension method that prevents this by saturating:

public static decimal ToDecimalSafe(this double input)
{
    try
    {
        return (decimal)input;
    }
    catch (OverflowException)
    {
        if (input < 0)
            return decimal.MinValue;
        else
            return decimal.MaxValue;
    }
}

The issue is, this overflow happens pretty often in my use case, breaking the "exceptions should be exceptional" guideline. This slows down the application, yes, but that's not terribly important. The real issue is it also causes lots of first-chance exceptions during debugging, which is annoying. Here's attempt number two, which seems to be working fine:

public static decimal ToDecimalSafe(this double input)
{
    if (input < (double)decimal.MinValue)
        return decimal.MinValue;
    if (input > (double)decimal.MaxValue)
        return decimal.MaxValue;

    try
    {
        return (decimal)input;
    }
    catch (OverflowException)
    {
        if (input < 0)
            return decimal.MinValue;
        else
            return decimal.MaxValue;
    }
}

I left the try-catch to make sure I catch some possible edge cases. The question here is: are there any edge cases or can I just omit the try-catch?

Can a double be >= (double)decimal.MinValue and <= (double)decimal.MaxValue and still cause an overflow when converting?

Answer 1

The exception will not happen anymore. You can modify your code in this way.

public static decimal ToDecimalSafe(this double input)
{
    if (input < (double)decimal.MinValue)
        return decimal.MinValue;
    else if (input > (double)decimal.MaxValue)
        return decimal.MaxValue;
    else
        return (decimal)input;
}

You can also use the specific convert method but it does not prevent the exception

Convert.ToDecimal

If your problem is just the debugging break that is annoying then I suggest to take a look at [DebuggerStepThrough] or [DebuggerHidden] attributes

Answer 2

我使用了cristallo的答案，它对我有用，唯一的提示是您也应该考虑NaN。