Convert a hex string to a byte in C#

Question

I have a String like this:

String data = "0x0f";

and I would like to leave it as a single byte which represents this hex. Does anyone know what function I can use?

I tried using the following function:

public byte pegarValorHexText(string text)
{
    int NumberChars = text.Length;
    byte[] bytes = new byte[NumberChars / 2];
    for (int i = 0; i < NumberChars; i += 2)
        bytes[i / 2] = Convert.ToByte(text.Substring(i, 2), 16);
    return bytes[0];
}

Does this answer your question? [Converting string to byte array in C#](https://stackoverflow.com/questions/16072709/converting-string-to-byte-array-in-c-sharp) — Hogan, Jan 24 '23 at 17:37
@Hogan I think the goal is to preserve the bytes which are written as hex to string. — Guru Stron, Jan 24 '23 at 17:40
@GuruStron no idea what you mean -- the answer I linked converts a string to bytes — Hogan, Jan 24 '23 at 17:41
@Hogan the string clearly has bytes written as hex values. Those needed to be translated back to bytes. — Guru Stron, Jan 24 '23 at 17:43
@OtávioZordanAlves can you please explain a little bit more. What if there are more then 1 byte stored in the string, the goal is to get only the first one or what? Does it have maximum length? — Guru Stron, Jan 24 '23 at 17:44
What version of .NET are you targeting? [`Convert.FromHexString(data.Replace("0x", ""))[0]` is available since .NET 5](https://learn.microsoft.com/en-us/dotnet/api/system.convert.fromhexstring?view=net-5.0#system-convert-fromhexstring(system-string)) — Mathias R. Jessen, Jan 24 '23 at 17:47
@Guru Stron The string has a hexadecimal value, it has a maximum of 4 characters, the sequence "0x" indicating that it is a hexadecimal value and a sequence of two hex chars — Otávio Zordan Alves, Jan 24 '23 at 17:47

score 2 · Accepted Answer · answered Jan 24 '23 at 17:55

The string has a hexadecimal value, it has a maximum of 4 characters, the sequence "0x" indicating that it is a hexadecimal value and a sequence of two hex chars

Just use Convert.ToByte then, it should handle the hex prefix:

byte b = Convert.ToByte("0x0f", 16); // 15

Convert a hex string to a byte in C#

1 Answers1