CODEWITHSUNDEEP
c#arrayshex
Eric Wood
Eric Wood

Reputation: 361

C# - Convert hex string to byte array of hex values

This question looks like a bunch of other questions, but none exactly match what I need. The problem with the other related questions seem to do an implicit conversion to decimal based on Visual Studio's IntelliSense.

Goal: Trying to convert hex string to byte array of hex values (not decimal values) in C#.

public static byte[] ConvertHexValueToByteArray() 
{
  string hexIpAddress = "0A010248"; // 10.1.2.72 => "0A010248"
  byte[] bytes = new byte[hexIpAddress.Length / 2];

  for (int i = 0; i < hexIpAddress.Length; i += 2)
  {
    string s2CharSubStr = hexIpAddress.Substring(i, 2);  // holds "0A" on 1st pass, "01" on 2nd pass, etc.

    if ((s2CharSubStr.IsAllDigit()) && (int.Parse(s2CharSubStr) < 10)) // fixes 0 to 9
      bytes[i / 2] = (byte) int.Parse(s2CharSubStr); // same value even if translated to decimal
    else if (s2CharSubStr.IsAllDigit()) // fixes stuff like 72 (decimal) 48 (hex)
      bytes[i / 2] = Convert.ToByte(s2CharSubStr, 10); // does not convert, so 48 hex stays 48 hex. But will not handle letters.
    else if (s2CharSubStr[0] == '0') // handles things like 10 (decimal) 0A (hex) 
      bytes[i / 2] = // ?????????????????????????????
    else // handle things like AA to FF (hex)
      bytes[i / 2] = // ?????????????????????????????
   }

   return bytes;
 }

Answers like the two below do implicit conversions (as viewed in Visual Studio's IntelliSense) from the hex to decimal AND/OR fail to handle the alpha part of the hex: 1) 

bytes[i / 2] = (byte)int.Parse(sSubStr, NumberStyles.AllowHexSpecifier);

2) 

bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);

3) bytes[i / 2] = Convert.ToByte(hexIpAddress.Substring(i, 2));

So I would like the function to return the equivalent of this hard-coded byte array: 

byte[] currentIpBytes = {0x0A, 01, 02, 0x48};

Upvotes: 0

Views: 15562

Answers (2)

payam purchi
payam purchi

Reputation: 276

private string DateToHex(DateTime theDate)
{
    string isoDate = theDate.ToString("yyyyMMddHHmmss");

    string resultString = string.Empty;

    for (int i = 0; i < isoDate.Length ; i++)    // Amended
    {
        int n = char.ConvertToUtf32(isoDate, i);
        string hs = n.ToString("x");
        resultString += hs;
    }
    return resultString;
}

Upvotes: 1

Ren&#233; Vogt
Ren&#233; Vogt

Reputation: 43876

string hexIpAddress = "0A010248"; // 10.1.2.72 => "0A010248"
byte[] bytes = new byte[hexIpAddress.Length / 2];

for (int i = 0; i < hexIpAddress.Length; i += 2)
    bytes[i/2] = Convert.ToByte(hexIpAddress.Substring(i, 2), 16);

This results in this array:

bytes = {0x0A, 0x01, 0x02, 0x48};

or represented as decimals:

bytes = {10, 1, 2, 72};

or as binaries 00001010, 000000001, 00000010, 01001000 (binary literals are still not supported in C#6).

The values are the same, there is no representation in any base in byte. You can only decide how the values should be represented when converting them to strings again:

foreach(byte b in bytes)
    Console.WriteLine("{0} {0:X}", b);

results in

10 A
1 1
2 2
72 48

Upvotes: 3

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