binaryWrite

 public struct testStram
        {
            public int userid;
            public int funid;
            public int limitStyle;
            [MarshalAs(UnmanagedType .ByValTStr,SizeConst=32)]//
            public string buffur;//预留32位

        }
        private void Form1_Load(object sender, EventArgs e)
        {

            testStram[] ts = new testStram[10];
            for (int i = 0; i < ts.Length; i++)
            {
                ts[i].userid = i;
                ts[i].funid = i;
                ts[i].limitStyle = i;
                ts[i].buffur = "14";
            }
            FileInfo fi = new FileInfo(@"D:\testbinaryReader.dat");
            using(BinaryWriter bw=new BinaryWriter (fi.OpenWrite()))
            {
                 for (int i = 0; i < ts.Length; i++)
                 {
                     bw.Write(ts[i].userid);
                     bw.Write(ts[i].funid);
                     bw.Write(ts[i].limitStyle);
                     bw.Write(ts[i].buffur);
                 }
            }