Match patterns

[Lupo73]

I'm trying to create a function that check if a string (as a file name) match with a particular pattern defined by the user.

At the moment I used this simply couple of lines:

$pattern = StringReplace($str, "*", "(.*?)")

$match = StringRegExp($item, $pattern)

$match results 1 if strings match and 0 otherwise. It works fine, but now I have found a problem: if for example is $str = "*.txt" the StringRegExp function return 1 for both $item = "item.txt" and $item = "item.txt.zip" (and so even if it doesn't correctly match).

Instead I need that if is "*.txt*" it is correct that both match (because the check is made with "(.*?).txt(.*?)"), but if there isn't the second asterisk, the match may return 0. How can I resolve this issue?

Thanks!

[Authenticity]

Use anchors.

$pattern = StringReplace($str, "*", "(.*?)") & "$"
$match = StringRegExp($item, $pattern)

...so it matches only at the end of the string, or "\b" to match at a word boundary. Or maybe something more restrictive, "(?i)[^a-z0-9_.]", etc..

On the other side, .*? can match easily file names such as ".txt" and "..txt" but it's something else.

Edited November 15, 2009 by Authenticity

[Lupo73]

It works fine, but now I need to do the same if the pattern is for example something*.*

In this case I can't add $ at the pattern beginning, but it works wrongly because both "something2.zip" and "2something.zip" match fine (but the second string may not match).

Sorry, but the pattern system is a little complex (for example adding $ to limit the checking is not reported in Help). What I need is to make a normal pattern checking, that allow extra characters only under * and not also at the begin or the end of a string. Thanks for the help

[GEOSoft]

According to the help file "$" matches at the end of the string and "^" matches at the beginning of the string.

(?i)(\b\w+\.[[:alnum:]]+\b

Edit: Correction in the SRE

Edited November 16, 2009 by GEOSoft

[Lupo73]

Good, this solution seems to work fine:

$pattern = StringReplace($str, "*", "(.*?)")

$match = StringRegExp($item, "^" & $pattern & "$")

What is the purpose of this string you have wrote?

(?i)(\b\w+\.[[:alnum:]]+\b

[GEOSoft]

Good, this solution seems to work fine:

$pattern = StringReplace($str, "*", "(.*?)")

$match = StringRegExp($item, "^" & $pattern & "$")

What is the purpose of this string you have wrote?

(?i)(\b\w+\.[[:alnum:]]+\b

(?i) = Case-insensitive

\b = match at word boundary

\w+ = match any word characters (a-z0-9_) one or more times

\. = match a literal "."

[[:alnum:]]+ = match any alpha-numeric (a-z0-9) characters 1 or more times

\b = match at word boundary

[Lupo73]

Uhm.. and I could use it instead of the actual mode? Can you insert it in my example? Thanks