Convert binary to signed int/decimal

Question

I am trying to convert hex data to signed int/decimal and can't figure out what I'm doing wrong.

I need FE to turn into -2.

I'm using Convert.ToInt32(fields[10], 16) but am getting 254 instead of -2.

Any assistance would be greatly appreciated.

Can you explain why you want to turn FE into -2 instead of 254 and how do you know that you need to get -2 instead of 254? — George Alexandria
– George Alexandria, Commented Sep 13, 2017 at 17:26
The guy I'm working with wants to see a signed value, not sure why but that's what was requested. It's possible though. This link does it in JavaScript. free-test-online.com/binary/signed_converter.html — StarScr3am77
– StarScr3am77, Commented Sep 13, 2017 at 17:29
That is not a signed int decimal - it's a signed byte if you want to read it that way. — Michael Dorgan
– Michael Dorgan, Commented Sep 13, 2017 at 17:29

Tyler Lee · Accepted Answer · 2017-09-13 17:32:45Z

4

int is 32 bits wide, so 0xFE is REALLY being interpreted as 0x000000FE for the purposes of Convert.ToInt32(string, int), which is equal to 254 in the space of int.

Since you're wanting to work with a signed byte range of values , use Convert.ToSByte(string, int) instead (byte is unsigned by default, so you need the sbyte type instead).

Convert.ToSByte("FE",16)

edited Sep 13, 2017 at 17:32

answered Sep 13, 2017 at 17:29

Tyler Lee

2,82517 silver badges24 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

mitaness · Accepted Answer · 2017-09-13 17:45:32Z

2

Interpret the value as a signed byte:

sbyte value = Convert.ToSByte("FE", 16); //-2

edited Sep 13, 2017 at 17:45

answered Sep 13, 2017 at 17:29

mitaness

7257 silver badges13 bronze badges

Comments

willeM_ Van Onsem · Accepted Answer · 2017-09-13 17:30:21Z

0

Well the bounds of Int32 are -2 147 483 648 to 2 147 483 647. So FE matches 254.

In case you want to do a wrap around over 128, the most elegant solution is proably to use a signed byte (sbyte):

csharp> Convert.ToSByte("FE",16);   
-2

answered Sep 13, 2017 at 17:30

willeM_ Van Onsem

482k33 gold badges483 silver badges624 bronze badges

Collectives™ on Stack Overflow

Convert binary to signed int/decimal

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related