Using Regex for file name matching?

[Chris1701 0]

I'm trying to figure out how to use regular expressions to test file names for matching results and the test program that I have is failing rather badly. It's basically a form with some labels / TEdits / a listbox and a button, so enter the pattern in the pattern tedit and enter the text in the text tedit and click the test button to see if it matches:

procedure TMainForm.TestClick(Sender: TObject);

begin
  If TRegEx.IsMatch( edText.Text, edPattern.Text ) Then
    lbData.Insert( 0, 'True' )
   Else
    lbData.Insert( 0, 'False' );
end;

For example if I enter "*.pas" in the edPattern edit and "myfiletest.pas" in edPattern and click Test the program throws an error "Project RegExpressText.exe raised exception class ERegularExpressionError with message 'Error in regular expression at offset 0: nothing to repeat'." So none of the things I see to try such as pattern "*mydata*.*" and text "thisismydata.csv" generate the same error however the preloaded test data Pattern "Er*" and text "Er S01 D01" does not cause and error and comes back True. What am I doing wrong here?

 

Thanks!

[Lajos Juhász 239]

A short answer is that *.pas is not a regular expression.  In this case:  *   The asterisk indicates zero or more occurrences of the preceding element. For example, ab*c matches "ac", "abc", "abbc", "abbbc", and so on.

 

[Lajos Juhász 239]

If you want to compare against file mask you should use https://docwiki.embarcadero.com/Libraries/Alexandria/en/System.Masks.MatchesMask.

 

For example:

 

 

uses
   System.Masks;

procedure TMainForm.TestClick(Sender: TObject);
begin
  if MatchesMask(edText.Text, EdPattern.Text) then
    lbData.Insert( 0, 'True' )
  Else
    lbData.Insert( 0, 'False' );
end;

 

 

[Chris1701 0]

Thanks that's very helpful!