Convert string element to byte

Question

I am trying to convert a string into a byte array. When I look at individual elements of the The byte array I get unexpected results. For example, when I look at the first element, which was "F", I expect it to be converted to 15, but instead I get 102. Is there an error here?

 Console.WriteLine("string[0] = " + string[0]);
 Byte[] data = Encoding.ASCII.GetBytes(string);
 Console.WriteLine("data[0] = " + data[0]);

 string[0] = f
 data[0] = 102

Why do you expect it to be 15? If anything I would expect it to be 70. Also please post a complete complieable example of the problem, right now your code would not even compile. EDIT: thanks Rik, 102 is f, I checked F. — Scott Chamberlain
– Scott Chamberlain, Commented Nov 1, 2013 at 15:38
By the way, beware of Unicode. C# strings are UTF16, and can take up to two bytes. — Max Yankov
– Max Yankov, Commented Nov 1, 2013 at 15:42

Hans Keﬆing · Accepted Answer · 2013-11-01 15:39:46Z

4

That ASCII.GetBytes returns the ASCII codes of the characters. It would happily accept a string "z{}".

I guess you want to convert a hexadecimal string to the integer value. You need Int32.Parse for that, with the NumberStyles parameter set to NumberStyles.HexNumber.

string s = "1F";
int val = Int32.Parse(s, System.Globalization.NumberStyles.HexNumber);

val would now be 31.

answered Nov 1, 2013 at 15:39

Hans Keﬆing

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2 Comments

Ann Over a year ago

Thanks, this is exactly what I needed. Is there a way to use it for chars as well? I am trying with no luck so far.

Hans Keﬆing Over a year ago

You could use the .ToString() method to convert the char into a string. Then you can parse it. Or just use a switch for those 16 values (guessing that it's a '0' through 'F').

David Arno · Accepted Answer · 2013-11-01 15:40:13Z

2

Lower case f is 102. Upper case F is 70. Please check http://www.asciitable.com

When you say you were expecting 15, my guess is you saw F in the hex column...

answered Nov 1, 2013 at 15:40

David Arno

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Comments

Rob · Accepted Answer · 2013-11-01 15:40:40Z

2

Are you expecting 15 because you've looked at something like asciitable.com and seen that the Hex decimal value for the HEX value 'F' is 15?

The decimal value for 'f' is 102 (it's part way down the fourth column in the linked page).

answered Nov 1, 2013 at 15:40

Rob

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Comments

Sudhakar Tillapudi · Accepted Answer · 2013-11-01 15:58:20Z

0

your expectation is wrong , your code is working fine, Decimal value for lower case 'f' is 102.

answered Nov 1, 2013 at 15:58

Sudhakar Tillapudi

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