How-to-Split-and-Merge-Files-using-Delphi-code


            Title: How to Split and Merge Files using Delphi code
There are times when you need to split a large file into several smaller ones (for whatever the purpose is). The following two methods use Delphi TStream objects to break a file into several files with predefined size; and to merge those files back to the original.
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procedure SplitFile(FileName : TFileName; FilesByteSize : Integer) ;
// FileName == file to split into several smaller files
// FilesByteSize == the size of files in bytes
var
 fs, ss: TFileStream;
 cnt : integer;
 SplitName: String;
begin
 fs := TFileStream.Create(FileName, fmOpenRead or fmShareDenyWrite) ;
 try
 for cnt := 1 to Trunc(fs.Size / FilesByteSize) + 1 do
 begin
 SplitName := ChangeFileExt(FileName, Format('%s%d', ['._',cnt])) ;
 ss := TFileStream.Create(SplitName, fmCreate or fmShareExclusive) ;
 try
 if fs.Size - fs.Position 
 FilesByteSize := fs.Size - fs.Position;
 ss.CopyFrom(fs, FilesByteSize) ;
 finally
 ss.Free;
 end;
 end;
 finally
 fs.Free;
 end;
end;
Note: a 3 KB file 'myfile.ext' will be split into 'myfile._1', 'myfile._2','myfile._3' if FilesByteSize parameter equals 1024 (1 KB). 
procedure MergeFiles(FirstSplitFileName, OutFileName : TFileName) ;
// FirstSplitFileName == the name of the first piece of the split file
// OutFileName == the name of the resulting merged file
var
 fs, ss: TFileStream;
 cnt: integer;
begin
 cnt := 1;
 fs := TFileStream.Create(OutFileName, fmCreate or fmShareExclusive) ;
 try
 while FileExists(FirstSplitFileName) do
 begin
 ss := TFileStream.Create(FirstSplitFileName, fmOpenRead or fmShareDenyWrite) ;
 try
 fs.CopyFrom(ss, 0) ;
 finally
 ss.Free;
 end;
 Inc(cnt) ;
 FirstSplitFileName := ChangeFileExt(FirstSplitFileName, Format('%s%d', ['._',cnt])) ;
 end;
 finally
 fs.Free;
 end;
end;
Usage:
SplitFile('c:\mypicture.bmp', 1024) ; //into 1 KB files 
...
MergeFiles('c:\mypicture._1','c:\mymergedpicture.bmp') ;
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Files Delphi
