Regular expression different result - html

Question

Hello I want match a table tag, followed by any characters but not another table, followed by an element with id ContentPlaceHolder1 and finally followed by the /table closed tag.
I write this reg exp:
~\<table[^>]*>.*?ContentPlaceHolder1.+?<\/table>~is
In my text editor (Emeditor) work fine, in PHP script this match the first table tag of page and al the followed code.
Can anyone tell me what's wrong?
Tks a lot

Answer 1

I am just assuming what you wish to achieve, and as Matt has commented on your question, a code snippet with an explanation of what exactly you are trying to achieve would help us help you.
So, in that context, I will try to guess the issue:
I'm guessing that your code has an element with id ContentPlaceHolder1 near the end and maybe nowhere else. What is leading me to assume that is that you are stating:
in PHP script this match the first table tag of page and al the followed code.
and also
want match a table tag, followed by any characters but not another table
Though this is not the case. In fact your regex is doing the following:
Match the first <table> tag with any attributes there might be inside it ([^>]*)
Match any character as few times as possible (.*?)
Match ContentPlaceHolder1
Match at least one character to any, but as few as possible to make a match (.+?)
Match a closing <\/table> tag
What I tend to believe you are misinterpreting is step #2. What this step is trying to achieve, is not to ignore leading <table> tags, but instead ignore multiple occurrences of the keyword ContentPlaceHolder1.
Consider the following example (please ignore that the html is broken, it's just an example):
<table border="3" cellpadding="10" cellspacing="10">
<td>
<table border="3" cellpadding="3" cellspacing="3">
<td>2nd table</td>
<some_element id="ContentPlaceHolder1"></some_element>
</table>
<td>2nd table</td>
<tr>
<td>2nd table</td>
<td>2nd table</td>
</tr>
</table>
<some_element id="ContentPlaceHolder1"></some_element>
</td>
<td> the cell next to this one has a smaller table inside of it, a table inside a table.</td>
</table>
Here, .*? is not instructing the regex engine to avoid matching a second <table> tag, what is instructing instead is to match the first occurence of the keyword ContentPlaceHolder1 instead of greedily matching the last one.
What you are trying to achieve, can be achieved using Negative Lookahead. What this implies, is that it instructs the regex engine, to look further away and assure that it doesn't match the first subset, if the second one exists. You can see this in practice in this demo, where I'm using negative lookahead to instruct the regex engine to only match a <table> tag if it is not followed by another <table> tag (<table[^>]*>(?!.*<table[^>]*>).
Please review my answer, and if it does solve your issue, please add more information and a sample of your code so that we can provide further assistance.
Regards

Answer 2

tks for the answere
This is an ipotetical page code:
<table border="3" cellpadding="10" cellspacing="10">
<tr>
<td>aaaaa</td>
</tr>
</table>
<table border="3" cellpadding="10" cellspacing="10">
<tr>
<td>aaaaa</td>
</tr>
</table>
<table border="3" cellpadding="10" cellspacing="10">
<tr>
<td>
<!-- from here -->
<table border="3" cellpadding="3" cellspacing="3">
<tr>
<td>aaaa</td>
<td><a id="ContentPlaceHolder1">link</a></td>
</tr>
</table>
<!-- to here -->
</td>
</tr>
</table>
<table border="3" cellpadding="10" cellspacing="10">
<tr>
<td>aaaaa</td>
</tr>
</table>
<table border="3" cellpadding="10" cellspacing="10">
<tr>
<td>aaaaa</td>
</tr>
</table>
I want to match from the first comment to the second.
In other word I want to match the complete table that contains elemnt with ContentPlaceHolder1 id.
My regexp in PHP match the first page table tag.
Tks a lot