Converting from hex to string

user_81800 0
Viewed 186196

I need to check for a string located inside a packet that I receive as byte array. If I use BitConverter.ToString(), I get the bytes as string with dashes (f.e.: 00-50-25-40-A5-FF).
I tried most functions I found after a quick googling, but most of them have input parameter type string and if I call them with the string with dashes, It throws an exception.

I need a function that turns hex(as string or as byte) into the string that represents the hexadecimal value(f.e.: 0x31 = 1). If the input parameter is string, the function should recognize dashes(example "47-61-74-65-77-61-79-53-65-72-76-65-72"), because BitConverter doesn't convert correctly.

bitconverter hex string c#
8 Answers

Like so?

static void Main()
{
    byte[] data = FromHex("47-61-74-65-77-61-79-53-65-72-76-65-72");
    string s = Encoding.ASCII.GetString(data); // GatewayServer
}
public static byte[] FromHex(string hex)
{
    hex = hex.Replace("-", "");
    byte[] raw = new byte[hex.Length / 2];
    for (int i = 0; i < raw.Length; i++)
    {
        raw[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
    }
    return raw;
}
Marc_Gravell_233540 
string str = "47-61-74-65-77-61-79-53-65-72-76-65-72";
string[] parts = str.Split('-');

foreach (string val in parts)
{ 
    int x;
    if (int.TryParse(val, out x))
    {
         Console.Write(string.Format("{0:x2} ", x);
    }
}
Console.WriteLine();

You can split the string at the -
Convert the text to ints (int.TryParse)
Output the int as a hex string {0:x2}

Ian_Quigley_524580

Your reference to "0x31 = 1" makes me think you're actually trying to convert ASCII values to strings - in which case you should be using something like Encoding.ASCII.GetString(Byte[])

user_9870

My Net 5 solution that also handles null characters at the end:

hex = ConvertFromHex( hex.AsSpan(), Encoding.Default );

static string ConvertFromHex( ReadOnlySpan<char> hexString, Encoding encoding )
{
    int realLength = 0;
    for ( int i = hexString.Length - 2; i >= 0; i -= 2 )
    {
        byte b = byte.Parse( hexString.Slice( i, 2 ), NumberStyles.HexNumber, CultureInfo.InvariantCulture );
        if ( b != 0 ) //not NULL character
        {
            realLength = i + 2;
            break;
        }
    }
    
    var bytes = new byte[realLength / 2];
    for ( var i = 0; i < bytes.Length; i++ )
    {
        bytes[i] = byte.Parse( hexString.Slice( i * 2, 2 ), NumberStyles.HexNumber, CultureInfo.InvariantCulture );
    }

    return encoding.GetString( bytes );
}
user_81514180

One-liners:

    var input = "Hallo Hélène and Mr. Hörst";
    var ConvertStringToHexString = (string input) => String.Join("", Encoding.UTF8.GetBytes(input).Select(b => $"{b:X2}"));
    var ConvertHexToString = (string hexInput) => Encoding.UTF8.GetString(Enumerable.Range(0, hexInput.Length / 2).Select(_ => Convert.ToByte(hexInput.Substring(_ * 2, 2), 16)).ToArray());
    Assert.AreEqual(input, ConvertHexToString(ConvertStringToHexString(input)));
user_65226690
Related