String.Contains doesnt work as expected with folders returned by Directory.GetDirectories

Question

For some reason, this statement completely bypasses folders which contain said text, what am I doing wrong?

For Each fold As String In Directory.GetDirectories("C:\documents")
    If fold.Contains("pdf") Then

I have folders in the c:\documents folder with names such as:

pdfone
pdfretrieve
extrapdf

When VS reads through, I see the strings:

"c:\documents\pdfone"
"c:\documents\pdfretrieve"
"c:\documents\extrapdf"

But it reads right past them and doesn't enter the If statement.

This works great here. Are you sure your "fold" contains what you think? — the_lotus, Jun 02 '15 at 14:00
can also change to `If fold.ToLower().Contains("pdf") Then`, although the answer below is a better approach — RianBattle, Jun 02 '15 at 14:35
@RianBattle: apart from the fact that this creates unnecessary string garbage in memory it is also prone to localization issues like the [turkish i problem](http://www.moserware.com/2008/02/does-your-code-pass-turkey-test.html). So using `ToUpper`/`ToLower` [is not the best approach](http://stackoverflow.com/questions/234591/upper-vs-lower-case) to provide case-insensitivity. — Tim Schmelter, Jun 02 '15 at 14:40
@TimSchmelter I wasn't aware of that at all, thanks for the info (this is why I like StackOverflow!) — RianBattle, Jun 02 '15 at 15:00

Tim Schmelter · Accepted Answer · 2015-06-02T14:20:05.263

Yes, it's PDFone. Is the .Contains property case sensitive?

String.Contains is case-sensitive (like most methods in the .NET framework). You have to use String.IndexOf if you want to ignore the case:

If fold.IndexOf("pdf", StringComparison.InvariantCultureIgnorecase) >= 0 Then

MSDN mentions it here:

this method performs an ordinal (case-sensitive and culture-insensitive) comparison. The search begins at the first character position of this string and continues through the last character position.

As an aside, GetDirectories returns the directory-name including their paths. So searching for substrings on the complete path is error-prone. Instead you could use Path.GetFileName(yes, not GetDirectoryName since that returns the parent directory, that's mentioned in the remarks):

If Path.GetFileName(fold).IndexOf("pdf", StringComparison.InvariantCultureIgnorecase) >= 0 Then

New to vb.net here and still getting used to case sensitivity. Thanks! — Gmac, Jun 02 '15 at 14:09
@Gmac: you're welcome. Note that i've edited my answer to show a better approach. — Tim Schmelter, Jun 02 '15 at 14:14

String.Contains doesnt work as expected with folders returned by Directory.GetDirectories

1 Answers1