Forum Discussion

gongyan's avatar
gongyan
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's avatar
    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?
farismalaeb's avatar
farismalaeb
Iron Contributor
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's avatar
    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's avatar
      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&amp;page=2

      and the (?<=a href="\.\.\/\.\.\/\.\.\/).+?(?=">2<) match withread.php?tid=4651187&amp;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's avatar
        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.

  • gongyan's avatar
    gongyan
    Copper Contributor
    Dec 25, 2021

    farismalaeb

     

    Hello, thank you for your reply!

    $url_1_context is the html source code of a web page. I use the regular expression $url_0_0_regex to match, and output the value of $Matches by judging the result of -match if($result_bool ), but obviously, the value of $Matches is another- The value after the match operation; it matches another regular expression, but does not match the regular expression represented by $url_0_0_regex.

    In addition, it should be noted that the code here is in a function (get_content), and this function (get_content) is called by another function (get_url_name), before calling this function (get_content), once- match operation.

     

     

Resources