CODEWITHSUNDEEP
c#regexvb.net
Ahmed ilyas
Ahmed ilyas

Reputation: 5822

Regex from VB to C# (LIKE to Regex)

So, VB6/VB.NET has a Like keyword, which is kind of like a Regex.

I know what this is doing but I am not an expert in Regex and was hoping someone could kindly help (AND I want to use Regex and not string specific stuff like IndexOf/get the last char):

VB code:

If (someDataStr Like "[*]??????????????8") Then
 ...
end if

So I am focusing on this:

"[*]??????????????8"

what would this be in terms of a Regex expression?

Upvotes: 3

Views: 1067

Answers (2)

Zarepheth
Zarepheth

Reputation: 2593

Building on Martin Büttner's answer, this is what I did to convert the VB Like operator into a C# Regex. As the Like operator in Visual Studio 2013 supports some additional Regular Expression like features, there is a bit of extra work to convert the pattern.

// escape RegEx special characters
var pattern = Regex.Escape(likePattern);
// convert negative character lists into RegEx negative character classes
pattern = Regex.Replace(pattern, @"\\\[!(?<c>[^\]]*)\\\]", @"[^${c}]", RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.ExplicitCapture);
// convert positive character lists into RegEx positive character classes
pattern = Regex.Replace(pattern, @"\\\[(?<c>[^\]]*)\\\]", @"[${c}]", RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.ExplicitCapture);
// convert asterisks into RegEx pattern for zero or more characters
pattern = Regex.Replace(pattern, @"(?<!\[[^\]]*)\\*(?![^\]*\])", @".*", RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.ExplicitCapture);
// convert question marks into RegEx pattern for any single character
pattern = Regex.Replace(pattern, @"(?<!\[[^\]]*)\\?(?![^\]*\])", @".", RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.ExplicitCapture);
// convert hash/number sign into RegEx pattern for any single digit (0 - 9)
pattern = Regex.Replace(pattern, @"(?<!\[[^\]]*)#(?![^\]*\])", @"[0-9]", RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.ExplicitCapture);
// make pattern match whole string with RegEx start and end of string anchors
pattern = @"^" + pattern + @"$";

// perform "like" comparison
return Regex.IsMatch(input, pattern, RegexOptions.IgnoreCase | RegexOptions.Singleline);

Warning: This code is has not been tested!

Upvotes: 0

Martin Ender
Martin Ender

Reputation: 44259

Based on Damien_The_Unbeliever's link, I assume that your pattern matches a literal *, 14 arbitrary characters and then a literal 8.

Then this would be your regex:

@"^\*.{14}8$"

Note that . will not generally match line breaks. If you need it to, then set the SingleLline option.

Match match = Regex.Match(input, @"^\*.{14}8$", RegexOptions.Singleline)

if (match.Success)
{
    // string has valid format
}

Upvotes: 9

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