How do I turn a string with random length in array of bytes C#

Question

I need to turn something like "0.014" in array of bytes, where first "0" = arr[0], "."= arr[1] and so on... and also turn them to Little Endian. My code works fine, but I have a problem with the length of the string and sometimes it gives out of bound exception Here is my code:

public void convertErrToByte(string errString, byte[] errToByte3)
    {              
        string errString2 = "";
        byte[] errToByte = new byte[errString.Length];
        byte[] errToByte2 = new byte[errString.Length];       
        
        for (int i = 0; i < errString.Length; i++)
        {
            errToByte[i] = Convert.ToByte(errString[i]); 
        }
        try
        {
            for (int i = 0; i < errToByte.Length - 1; i += 2) 
            {
                errToByte2[i] = errToByte[i + 1];
                errToByte2[i + 1] = errToByte[i];
            }
        }
        catch (Exception ex) { MessageBox.Show(ex.ToString()); }
        for (int i = 0; i < errToByte2.Length; i++)
        {
            errString2 += errToByte2[i].ToString("X"); 
        }

        for (int i = 0; i < errString2.Length; i++)
        {
            errToByte3[i] = Convert.ToByte(errString2[i]); 
        }
    }

Answer 1

Assuming you are using ASCII Encoding:

    private void swapBytePair(ref byte[] bytes)
    {
        if (bytes.Length == 0)
            return;

        byte temp;
        int len = (bytes.Length % 2 == 0) ? bytes.Length : bytes.Length - 1;

        for (int i=0; i < len; i+=2)
        {
            temp = bytes[i];
            bytes[i] = bytes[i + 1];
            bytes[i + 1] = temp;
        }
    }

    byte[] bytes = Encoding.ASCII.GetBytes("ABCDEFG");
    swapBytePair(ref bytes);
    //result: "BADCFEG"

I think you had issues with uneven string lengths, my method ignores the last byte, since there is nothing to swap with.