BinaryWriter problem - "code adds some byte between Write() method"

Question

I am try to do some code using BinaryWriter and Then BinaryReader. When I wanna write I use method Write(). But the problem is that between two lines of Write method there appears a new byte which is in ASCII table in decimal 31 (sometines 24). You can see it on this image:

You can see that byte at index 4 (5th byte) is of ASCII decimal value 31. I didnt insert it there. As you can see 1st 4 bytes are reserved for a number (Int32), next are other data (some text mostly - this is not important now).

As you can see from the code i write: - into 1st line a number 10 - into 2nd line text "This is some text..."

How come came that 5th byte (dec 31) in between??

And this is the code I have:

static void Main(string[] args)
    {           
        //
        //// SEND - RECEIVE:
        //
        SendingData();
        Console.ReadLine();
    }

    private static void SendingData()
    {
        int[] commandNumbers = { 1, 5, 10 }; //10 is for the users (when they send some text)!

        for (int i = 0; i < commandNumbers.Length; i++)
        {
            //convert to byte[]
            byte[] allBytes;
            using (MemoryStream ms = new MemoryStream())
            {
                using (BinaryWriter bw = new BinaryWriter(ms))
                {
                    bw.Write(commandNumbers[i]);   //allocates 1st 4 bytes - FOR MAIN COMMANDS!
                    if (commandNumbers[i] == 10)
                        bw.Write("This is some text at command " + commandNumbers[i]); //HERE ON THIS LINE IS MY QUESTION!!!
                }
                allBytes = ms.ToArray();
            }

            //convert back:
            int valueA = 0;
            StringBuilder sb = new StringBuilder();
            foreach (var b in GetData(allBytes).Select((a, b) => new { Value = a, Index = b }))
            {
                if (b.Index == 0) //1st num
                    valueA = BitConverter.ToInt32(b.Value, 0);
                else //other text
                {
                    foreach (byte _byte in b.Value)
                        sb.Append(Convert.ToChar(_byte));
                }
            }

            if (sb.ToString().Length == 0)
                sb.Append("ONLY COMMAND");
            Console.WriteLine("Command = {0} and Text is \"{1}\".", valueA, sb.ToString());
        }
    }

    private static IEnumerable<byte[]> GetData(byte[] data)
    {
        using (MemoryStream ms = new MemoryStream(data))
        {
            using (BinaryReader br = new BinaryReader(ms))
            {
                int j = 0;
                byte[] buffer = new byte[4];
                for (int i = 0; i < data.Length; i++)
                {
                    buffer[j++] = data[i];
                    if (i == 3) //SENDING COMMAND DATA
                    {
                        yield return buffer;
                        buffer = new byte[1];
                        j = 0;
                    }
                    else if (i > 3) //SENDING TEXT
                    {
                        yield return buffer;
                        j = 0;
                    }
                }
            }
        }
    }

Answer 1

If you look at the documentation for Write(string), you'll see that it writes a length-prefixed string. So the 31 is the number of characters in your string -- perfectly normal.