C#實現一次分割多個檔案

using System.IO;using System.Windows.Forms; OpenFileDialog dlg = new OpenFileDialog();dlg.Filter ="All files (*.*)|*.*";dlg.FilterIndex = 1;dlg.RestoreDirectory = true;dlg.Multiselect = true;if (dlg.ShowDialog() == DialogResult.OK){    foreach (string filetosplit in dlg.FileNames)    {            string targetpath="D:";            FileStream fsr = new FileStream(filetosplit, FileMode.Open, FileAccess.Read);            long FileLength=fsr.Length;            byte[] btArr = new byte[FileLength];            fsr.Read(btArr, 0, (int)FileLength);            fsr.Close();            long PartLength=FileLength/3+FileLength%3;            int nCount=(int)Math.Ceiling((double)FileLength/PartLength);            string strFileName=Path.GetFileName(filetosplit);            long byteCount=0;            for(int i=1;i<=nCount;i++,byteCount=(i
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