Author: Lou Adler

I am trying to write a simple backup utility for my projects. The utility 
recursivley searches folders looking for *.dpr files when it finds one it looks to 
see if a *.dof file is available and then extracts the FileVersion number from 
this, using this information it then creates a zip file with all the project files 
in it. It works so far and creates files like Project1-v1.0.0.0.zip. The problem is 
if the file already exists in the selected backup folder I wish to increment the 
file name so all versions are kept, e.g. if Project1-v1.0.0.0.zip already exists 
then generate a filename of Project1-v1.0.0.0-1.zip. If Project1-v1.0.0.0-1.zip 
exists then generate a file name Project1-v1.0.0.0-2.zip etc. to make sure no files 
are overwritten.

Answer:

Variants are the easiest way of dealing with these properties.
1   
2   function GetNextBackupFileName(AFolder, AFile: string): string;
3   var
4     v, v1: Integer;
5     Body, Ext: string;
6     sr: TSearchRec;
7   
8     function FileExt(FileName: string): string;
9     begin
10      Result := ExtractFileExt(FileName);
11    end;
12  
13    function FileBody(FileName: string): string;
14    begin
15      Result := ChangeFileExt(FileName, '');
16    end;
17  
18    function GetPostFix(FileName: string): Integer;
19    begin
20      Result := StrToIntDef(Copy(FileBody(FileName), Length(Body) + 1, 255), 0);
21    end;
22  
23  begin
24    Result := AFile;
25    v := 0;
26    Body := FileBody(AFile);
27    Ext := FileExt(AFile);
28    if FindFirst(AFolder + Body + '*' + Ext, faAnyFile xor faDirectory, sr) = 0 then
29    begin
30      repeat
31        v1 := GetPostFix(sr.Name);
32        if v1 < v then
33          v := v1;
34      until
35        FindNext(sr) <> 0;
36      FindClose(sr);
37      Result := Body + IntToStr(v - 1) + Ext;
38    end;
39  end;
40  
41  //Used like this:
42  
43  procedure TForm1.Button1Click(Sender: TObject);
44  var
45    BackupFolder, BaseFileName: string;
46  begin
47    BackupFolder := 'C:\BackupFolder\';
48    BaseFileName := 'Project1-v1.0.0.0.zip';
49    Label1.Caption := GetNextBackupFileName(BackupFolder, BaseFileName);
50    FileClose(FileCreate(BackupFolder + Label1.Caption));
51  end;