Cleanest way to check if a number is an integer.

[Chris_F]

What about

bool isNotInteger = (number > (float)((int)number);

You'd be casting the number to integer (removing fractions), then back to float to have the same data type for comparing. If your original number is greater than your truncated one, you have a fraction.
Would that work?

Converting a float to integer and then back to float is going to be very detrimental to performance. You are going to encounter a significant load-hit-store penalty. You should generally avoid casting floats <--> ints whenever possible.

You could try one of these two solutions:

bool isInteger(float num)
{
    return num % 1 == 0;
}

bool isInteger(float num)
{
    return (float)Math.Floor(num) == num;
}

I suspect the Math.Floor version will perform better, but you should check yourself.