Forum Discussion

Copper Contributor

Dec 24, 2021

Solved

Regarding the problem of -match not updating the $Matches variable after matching

这是我代码的一部分 $Matches = 0 $url_0_0_regex = '(?<=a href="\.\./\.\./\.\./).+?(?=">2<)' #$url_1_context #sleep -Seconds 50 $result_bool = $url_1_context -match $url_0_0_regex ...

Windows PowerShell

farismalaeb
Dec 24, 2021
$Matches hold the success matches and its a hashtable
maybe the 0 you are getting is the first key of the hashtable
try $Matches.Values
can you provide a string of matching?

gongyan

Copper Contributor

Dec 25, 2021

farismalaeb

It is possible to obtain the desired result correctly by matching alone; an example is as follows:

$a = '<tr><td align="left"><div class="pages"><a href="javascript&colon;#" class="gray">＜</a><a href="javascript&colon;#" class="gray">上一頁</a><a><U>1</U></a><a href="../../../read.php?tid=4651187&amp;page=2">2</a>'
$a -match 'a href="\.\./\.\./\.\./.+?(?=">2<)'
$Matches

out
True

Name                           Value                                                                                                                                                                                                                                                                                   
----                           -----                                                                                                                                                                                                                                                                                   
0                              a href="../../../read.php?tid=4651187&amp;page=2

So, I guess this may be more related to the scope of the variable, but I cannot change the scope of $Matches. Can the -match operation save the result to other custom variables instead of updating it to the $Matches variable?

farismalaeb

Iron Contributor

Dec 27, 2021

gongyan

I hope I understand your explination, but here are my finding.

The regex example you provide are different and surely they wont match.

Which one are you using '(?<=a href="\.\./\.\./\.\./).+?(?=">2<)' or'a href="\.\./\.\./\.\./.+?(?=">2<)'

I checked the result in regex101.com. The a href="\.\.\/\.\.\/\.\.\/.+?(?=">2<) match the following string a href="../../../read.php?tid=4651187&page=2

and the (?<=a href="\.\.\/\.\.\/\.\.\/).+?(?=">2<) match withread.php?tid=4651187&page=2

So which regex are you using and showing the wrong result.

I think you need to review your regex query, it doesn't matter if you are passing the result from one function to another.

gongyan
Copper Contributor
Jan 07, 2022
farismalaeb
Thank you for your answer.
I discovered later that this is caused by the differences in the implementation of regularization in different programming languages. I use notepad++ software to verify whether the regular expressions can match, but some regular expressions cannot match the expected results correctly in PowerShell.
And in the case of PowerShell, using the -match operator to match and the [regex::] class to match, in some cases, it is not possible to get consistent results.