C#, DETERMINE *if* a double can become an int without any loss [duplicate]

This question already has answers here: Closed 10 years ago.

Possible Duplicate:

How to determine if a decimal/double is an integer?

I have a unique situation in which all numbers must be saved as double data type in my database, but only in certain conditions is the precision beyond the integer level valuable.开发者_如何学运维

At first, I tried to just use int and then abstract to a new table when these unique fractional occurances would happen, but after doing that for weeks I can see now that it is excessively stupid and wasting my time.

I know that I can turn a double into an int. That is easy. I know how to translate it over. What I do not know is how to TEST for translating it over. I basically wish to come up with a short, easy way to say

Is this number really a double, or is it just an int?

If it is an int (and most of the time, it will be), then I will turn it into one and treat it as such. But due to the uniqueness of the requirements, I have to still save everything in the database as double.

Any ideas? I know this is a newbie question, and I've googled around for several hours and am still left quite confused.

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Cast it to an int and see if it's still equal:

if ((int)val == val)

(int)val will truncate any fractional portion.

Note that this may behave unexpectedly if the number is too large to retain complete precision in the double.

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double d = ...;

if(d == (int)d)
   //is int
else
  //is not int

Of course due to some precision issues, this may not work 100% times. You can use

double d = ...;

if(Math.Abs(d - (int)d) < Epsilon) //const double Epsilon = 0.000001;
   //is int
else
  //is not int

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This similar post shows you how to determine if a double or decimal has decimal places or not. You can use this to determine what type it is and then store appropriately.

Accepted answer from that post:

For floating point numbers, n % 1 == 0 is typically the way to check if there is anything past the decimal point.

public static void Main (string[] args)
{
    decimal d = 3.1M;
    Console.WriteLine((d % 1) == 0);
    d = 3.0M;
    Console.WriteLine((d % 1) == 0);
}

Output:

False
True

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try this

double x = ......

if (Math.truncate(x) == x)

....... (is integer, unless its so big its outside the bounds)