c#文件转化byte数组

   public static byte[] ReadFile(string fileName)
         {
             if (!File.Exists(fileName))
             {
                 throw new Exception("文件为空");
             }

             byte[] pReadByte = new byte[];
             try
             {
                 using (FileStream pFileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read))
                 {
                     BinaryReader r = new BinaryReader(pFileStream);

                     r.BaseStream.Seek(, SeekOrigin.Begin);    //将文件指针设置到文件开

                     pReadByte = r.ReadBytes((int)r.BaseStream.Length);

                     return pReadByte;
                 }

             }

             catch
             {

                 return pReadByte;

             }

         }