Author: Jonas Bilinkevicius

I am trying to find a function that will generate a temporary filename. I know that 
there is the GetTempFilename function, but I don't have any examples on how to use 
it.

Answer:

Solve 1:

1   procedure TForm1.Button1Click(Sender: TObject);
2   var
3     TempFile: array[0..MAX_PATH - 1] of Char;
4     TempPath: array[0..MAX_PATH - 1] of Char;
5   begin
6     GetTempPath(MAX_PATH, TempPath);
7     if GetTempFileName(TempPath, PChar('abc'), 0, TempFile) = 0 then
8       raise Exception.Create('GetTempFileName API failed. ' +
9         SysErrorMessage(GetLastError));
10    ShowMessage(TempFile);
11  end;


Note that this would actually create the temp file in the windows temp folder. 
Check online help for GetTempFileName, uUnique parameter for details.


Solve 2:

12  function MyGetTempFile(const APrefix: string): string;
13  var
14    MyBuffer, MyFileName: array[0..MAX_PATH] of char;
15  begin
16    FillChar(MyBuffer, MAX_PATH, 0');
17      FillChar(MyFileName, MAX_PATH, 0);
18      GetTempPath(SizeOf(MyBuffer), MyBuffer);
19      GetTempFileName(MyBuffer, APrefix, 0, MyFileName);
20      Result := MyFileName;
21  end;
22  
23  const
24    MyPrefix: string = '
25  
26  MyTempFile := MyGetTempFile(MyPrefix);



Solve 3:

Pass in the path and filename you want for the first parameter and your extension 
as the second. If you want the file to always be myfile1.tmp rather than myfile.tmp 
leave the last parameter, otherwise set it to false. E.g. to create a file like 
c:\Tempdir\MyTempFile2000.tmp
27  
28  sNewFileName := CreateNewFileName('C:\TempDir\MyTempFile', '.tmp');
29  
30  function CreateNewFileName(BaseFileName: string; Ext: string;
31    AlwaysUseNumber: Boolean = True): string;
32  var
33    DocIndex: Integer;
34    FileName: string;
35    FileNameFound: Boolean;
36  begin
37    DocIndex := 1;
38    Filenamefound := False;
39    {if number not required and basefilename doesn't exist, use that.}
40    if not (AlwaysUseNumber) and (not (fileexists(BaseFilename + ext))) then
41    begin
42      Filename := BaseFilename + ext;
43      FilenameFound := true;
44    end;
45    while not (FileNameFound) do
46    begin
47      filename := BaseFilename + inttostr(DocIndex) + Ext;
48      if fileexists(filename) then
49        inc(DocIndex)
50      else
51        FileNameFound := true;
52    end;
53    Result := filename;
54  end;


I simply checks if the file exists and returns the first that doesn't.