using System;using System.IO;string filetosplit=@"C:/temp/data.bin";string targetpath=@"D:/store";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();int splitcount=3;long PartLength=FileLength/splitcount+FileLength%splitcount;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<nCount?byteCount+PartLength:FileLength-PartLength)){  FileStream fsw = new FileStream(targetpath + Path.DirectorySeparatorChar+ strFileName +i, FileMode.Create, FileAccess.Write);  fsw.Write(btArr, (int)byteCount, (int)(i<nCount?PartLength:FileLength-byteCount));  fsw.Flush();  fsw.Close();}

using System;using System.IOstring filetosplit=@"C:/temp/data.bin";string targetpath=@"D:/store";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();int splitcount=3;long PartLength=FileLength/splitcount+FileLength%splitcount;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<nCount?byteCount+PartLength:FileLength-PartLength)){  FileStream fsw = new FileStream(targetpath + Path.DirectorySeparatorChar+ strFileName +i, FileMode.Create, FileAccess.Write);  long bc=byteCount;  long PartCount=i<nCount?PartLength:FileLength-bc;  int PartBufferCount=(int)(PartCount<int.MaxValue/32?PartCount:int.MaxValue/32);  int nc=(int)Math.Ceiling((double)PartCount/PartBufferCount);  for(int j=1;j<=nc;j++,bc=(j<nCount?bc+PartBufferCount:PartCount-PartBufferCount))    fsw.Write(btArr, (int)bc, (int)(j<nc?PartBufferCount:PartCount-bc));  fsw.Flush();  fsw.Close();}fsr.Close();