测试的一个内存流.为何停住?

//写入并读取.
        void WriteAndRead(object sender, EventArgs e) {
            byte[] bytesFromEncodingInput = Encoding.Default.GetBytes(txtInput.Text);   //选择默认编码.
            MemoryStream mStream = new MemoryStream(20);
            mStream.Write(bytesFromEncodingInput, 0, bytesFromEncodingInput.Length);    //写入内存流.
            richTxtProperties.Text = string.Format("分配给内存流的字节数为 {0},流长度为 {1},当前流位置为 {2}", mStream.Capacity, mStream.Length, mStream.Position);

            mStream.Seek(0, SeekOrigin.Begin);  //将流的位置设为最开始.
            int readPosition = 0;   //流的位置.
            while(readPosition < mStream.Length - 1) {
                byte[] bytesFromMStreamRead = new byte[5];  //流每次读取后存放的数组.
                mStream.Read(bytesFromMStreamRead, readPosition, bytesFromMStreamRead.Length);
                char[] cResult = new char[Encoding.Default.GetCharCount(bytesFromMStreamRead)]; //存放解析后的字节数组.
                Encoding.Default.GetChars(bytesFromMStreamRead, readPosition, bytesFromMStreamRead.Length, cResult, 0);
                foreach(var r in cResult) {
                    richTxtContent.Text += r.ToString();
                }
                mStream.Flush();    //情况缓冲区.
            }
        }
/*
为了能分段给用户返回内存读取数据,而不是一致性读取后返回给用户,我这样做.
我调试的时候,发现我的"richTxtContent"的Text"是我输入的哈....
但是运行的时候,无法回到页面.
 
 
*/

[解决办法]

  while(readPosition < mStream.Length - 1) <------------
{
                byte[] bytesFromMStreamRead = new byte[5];  //流每次读取后存放的数组.
                mStream.Read(bytesFromMStreamRead, readPosition, bytesFromMStreamRead.Length);
                char[] cResult = new char[Encoding.Default.GetCharCount(bytesFromMStreamRead)]; //存放解析后的字节数组.
                Encoding.Default.GetChars(bytesFromMStreamRead, readPosition, bytesFromMStreamRead.Length, cResult, 0);
                foreach(var r in cResult) {
                    richTxtContent.Text += r.ToString();
                }
                mStream.Flush();    //情况缓冲区.
            }

死循环了呀。readPosition 一直为0