为什么浮点运算在 C# PointF 中返回整数？

Question

I have the following statement which uses all flat data type.

ScaledCordinates.BottomRight = new PointF(((float)ScaleBottomRight.X * (float)Scale), ((float)ScaleBottomRight.Y * (float)Scale));

The values assigned to "ScaleBottomRight.X" is 2.36523485 and "ScaleBottomRight.Y" is 2.38020468 . "Scale" = 66.80098 .

I don't understand why "ScaledCordinates.BottomRight" is giving me {X = 158 Y = 159} in my app. Why is the float operation returns integer values? It's even frustrating some times output is an integer and some times float. I did all sorts of conversions between double and float but the same result. What's the best way to fix these issues? The output should be a "float" data type.

Answer 1

2.36523485 * 66.80098 = 158.000005910153

and

2.38020468 * 66.80098 = 159.0000052245864

They both have too small fractional part to fit in float precision, which is ~6-9 digits according to the docs . The result of multiplication is still float (ie System.Single ) though:

Console.WriteLine((2.36523485f * 66.80098f)); // prints "158"
Console.WriteLine((2.36523485f * 66.80098f).GetType()) // prints "System.Single"

Answer 2

I would assume that whatever Type ScaledCordinates.BottomRight is, its X and Y properties (of fields) are of Type int .

For example, it might be of Type Point , whose X and Y are int s: X docs . Y docs .

You can change it to a different Type. But as long as they are int s - you can't keep the floating point information.