Stream Reading

          The abstract Stream class is the base for all streams. It defines methods and properties for three fundamental operations : reading, writing, and seeking , as well as for administrative tasks such as closing , flushing, and configuring timeouts.
          Reading: 

        /**//// <summary>
        /// 从当前流读取序列字节,并且将次流的位置提升 count 个字节数.
        /// </summary>
        /// <param name="buffer">字节数组</param>
        /// <param name="offset">buffer字节数组的读取位置</param>
        /// <param name="count">读取的字节数量</param>
        /// <returns></returns>
        public abstract int Read(byte[] buffer, int offset,int count)

       /**////<summary>
       /// 从流中读取一个字节，并将流内的位置向前推进一个字节，或者如果已到达流的末尾，则返回 -1
       ///</summary>
       public virtual int ReadByte();

         例子:

           // 创建一个test.txt在当前路径下, test.txt 中的内容是 12345678
            using (var stream =new FileStream("test.txt",FileMode.OpenOrCreate))
            {
                var block = new byte[stream.Length];

                Console.WriteLine(stream.ReadByte()); // 49           //每次读一次 Position 的值自动加1
                Console.WriteLine(stream.ReadByte()); // 50

                stream.Position = 0;   // 把流位置设置为起始位置,经过上面 两行代码, Position 的值是2

                Console.WriteLine(stream.Read(block,0,block.Length)); //8
                Console.WriteLine(stream.Read(block, 0, block.Length)); //0      因为 Position 已经到了末尾
            }