5

I am trying to cast a float into a byte array of length 4, and then back again. But I it doesn's seems to work.

Here's what I've done:

byte[] b = BitConverter.GetBytes(90);
float fb = BitConverter.ToSingle(b, 0);

I expected fb = 90, but it's 1.26E-43.

I know that my converter is little endian, so I've also tried to reverse the array, like this:

byte[] b = BitConverter.GetBytes(90);
Array.Reverse(b);
float fb = BitConverter.ToSingle(b, 0);

Then I got the answer fb = 9.0E+15.

Any ideas? Thanks in advance!

random
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    `90` is an `int`, not a `float`. `90f` is a `float`. In either case, whatever you're doing here is quite possibly the wrong thing to do -- occasionally there is a useful need for converting a `float` into bytes using `BitConverter`, but for most serialization purposes it's actually not the right tool. – Jeroen Mostert Aug 26 '19 at 13:53

3 Answers3

8

BitConverter.GetBytes(90); will give you the bytes for the integer value of 90. Since you want the bytes for the float value, you need to specify that:

BitConverter.GetBytes((float)90.0);

or

BitConverter.GetBytes(90.0f);
D Stanley
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6

You need to change the input on the GetBytes, it's an integer now.

It's now getting the bytes on how the integer is stored and interpretate as how a float would be stored in memory.

Change it to a float.

Try: 

byte[] b = BitConverter.GetBytes(90f);  // <-- add an f for floats.
Array.Reverse(b);
float fb = BitConverter.ToSingle(b, 0);
Jeroen van Langen
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6

90 is a literal that is interpreted by the compiler as Int32, not as Single. So you call the wrong overload of GetBytes().

Use: byte[] b = BitConverter.GetBytes(90f);

to tell the compiler you want to call GetBytes(float).

René Vogt
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