How do I convert hex string into signed integer?

11,540

Solution 1

My solution was to put the first take the first 8 bits of the 16 bit integer and store them in an sbyte.

Solution 2

You can use Convert.ToSByte

For example:

string x = "aa";
sbyte v = Convert.ToSByte(x, 16);
// result: v = 0xAA or -86

You can also use sbyte.Parse

For example:

string y = "bb";
sbyte w = sbyte.Parse(y, System.Globalization.NumberStyles.HexNumber);
// result: w = 0xBB or -69

To answer your question about the upper or lower byte of an Int16:

string signed_short = "feff";

// Truncate 16 bit value down to 8 bit
sbyte b1 = (sbyte)Convert.ToInt16(signed_short, 16);
sbyte b2 = (sbyte)short.Parse(signed_short, System.Globalization.NumberStyles.HexNumber);
// result: b1 = 0xFF or -1
// result: b2 = 0xFF or -1

// Use upper 8 bit of 16 bit
sbyte b3 = (sbyte)(Convert.ToInt16(signed_short, 16) >> 8);
sbyte b4 = (sbyte)(short.Parse(signed_short, System.Globalization.NumberStyles.HexNumber) >> 8);
// result: b3 = 0xFE or -2
// result: b4 = 0xFE or -2

Solution 3

You need to perform an unchecked cast, like this:

sbyte negativeOne = unchecked((sbyte)255);
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alexD
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alexD

Updated on June 04, 2022

Comments

  • alexD
    alexD over 1 year

    I'm getting a hex string that needs to be converted to a signed 8-bit integer. Currently I'm converting using Int16/Int32, which will obviously not give me a negative value for an 8-bit integer. If I get the value 255 in Hex, how do I convert that to -1 in decimal? I assume I want to use an sbyte, but I'm not sure how to get that value in there properly.

  • Anton Kedrov
    Anton Kedrov almost 9 years
    I guess, it is because OP was asking to convert "STRING into signed integer". Anyway, your answer was helpful to me. Thank you! :)