using System; using System.IO; string filetomerge=@"C:\temp\data.bin"; string targetpath=@"D:\store"; string strFileName = filetomerge.Substring(filetomerge.LastIndexOf(Path.DirectorySeparatorChar) + 1); FileStream fsr1 = new FileStream(targetpath+ Path.DirectorySeparatorChar + strFileName + "1", FileMode.Open, FileAccess.Read); FileStream fsr2 = new FileStream(targetpath+ Path.DirectorySeparatorChar + strFileName + "2", FileMode.Open, FileAccess.Read); byte[] btArr = new byte[fsr1.Length+fsr2.Length]; fsr1.Read(btArr, 0, Convert.ToInt32(fsr1.Length)); fsr2.Read(btArr, Convert.ToInt32(fsr1.Length), Convert.ToInt32(fsr2.Length)); fsr1.Close(); fsr2.Close(); FileStream fsw = new FileStream(%%2 + Path.DirectorySeparatorChar+ strFileName, FileMode.Create, FileAccess.Write); fsw.Write(btArr, 0, btArr.Length); fsw.Flush(); fsw.Close();