C＃-十进制转换为整数并根据值取整

Question

I'm trying convert a decimal into integer and want to round the value up or down depending on the situation.

Basically example is:

• 12/3 = 4 so should round to 4
• 11/3 = 3.66666 so should round to 4
• 10/3 = 3 = 3.33333 so should round to 3
• 9/3 = 3 so should round to 3

Whatever I found on the internet always rounds down or always rounds up, never makes a judgment call based on the numbers.

Answer 1

If x is the number you want to round and you want the "normal" rounding behavior (so that .5 always gets rounded up), you need to use Math.Round(x, MidpointRounding.AwayFromZero) . Note that if you are actually computing fractions and the numerator and denominator are integers, you need to cast one of them to double first (otherwise, the division operator will produce an integer that is rounded down), and that if you want the result to be an int , you need to cast the result of Round() :

int a = 5;
int b = 2;
double answer = (int) Math.Round(a / (double) b, MidpointRounding.AwayFromZero);

Answer 2

Does Math.Round(d) do what you require?

Return Value: The integer nearest parameter d. If the fractional component of d is halfway between two integers, one of which is even and the other odd, the even number is returned. Note that this method returns a Decimal instead of an integral type.

Check out the Round reference page

Answer 3

Math.Round(value) should do what you want. Examples console app code to demonstrate:

Console.Write("12 / 3 = ");
Console.WriteLine((int)Math.Round(12d / 3d));
Console.WriteLine();

Console.Write("11 / 3 = ");
Console.WriteLine((int)Math.Round(11d / 3d));
Console.WriteLine();

Console.Write("10 / 3 = ");
Console.WriteLine((int)Math.Round(10d / 3d));
Console.WriteLine();

Console.Write("9 / 3 = ");
Console.WriteLine((int)Math.Round(9d / 3d));
Console.WriteLine();

Console.ReadKey();

Answer 4

You could try this

Math.Round(d, 0, MidpointRounding.AwayFromZero)

Sometime, people add 0.5 to the number before converting to int.