[PHP4BETA] perl compatible regex search&replace behaving oddly... bug? From: Alexander Fordyce (alex <email protected>)
Date: 01/18/00

Afternoon, all.

Is this a bug, or am I doing something wrong? (there's definitely
something wrong somewhere).

Perl compatible search&replace is not doing what it seems like it
should with with multiple \\n references. It will replace one
occurrence, but it goes crazy on more than one. I'm trying to use it
for simple variable interpolation:

- - - - - - - - - - - - - - -
$var1 = "contents1"; $var2 = "contents2";

$str = "<HTML><BODY>
this is one variable: #var1#,<BR>
and this is another: #var2#.
</BODY></HTML>";

echo preg_replace("/#([^#]+)#/e", "$\\1", $str);
- - output: - -
Parse error: parse error, expecting `T_VARIABLE' or `'$'' in
/tests/preg_test.html on line 0
this is one variable: contents1,
and this is another: .
- - - - - - - - - - - - - - -

I realize that the parse error occurs because it's not finding
anything nice and executable the second time around. Sometimes it
produces an ugly binary-looking garbage value for the second variable
-- it's a bit unpredictable.

It works fine with multiple non-referenced substitutions: e.g.
$str = preg_replace("/this/", "here", $str)
- - output: - -
here is one variable: #var1#,
and here is another: #var2#.

So is this a bug, or is it just a non-feature? It seems odd to
implement this function which has the equivalent of Perl's "/g" flag
forcibly turned on and then not allow references to work.

It seems like it should work, as that's the way it's presented in the
documentation. However, the example from the manual which is
supposed to upper-case html tags produces similar garbage when I copy
and paste the code:

- - - - - - - - - - - - - - -
$html_body = "<P>just some <strong>nice</strong> <b>simple</b> text</P>";
print preg_replace("/(<\/?)(\w+)([^>]*>)/e",
"'\\1'.strtoupper('\\2').'\\3'", $html_body);
- - output: - -
<P>just some rONG>NIcniceb> TEXT</ simple textó(;
- - - - - - - - - - - - - - -

(Btw, I know there are millions of ways to achieve the same or
similar effect, but I'm asking because this is one of the most
frequently used constructions in all my Perl programs, and the Perl
way is so much simpler and cleaner than anything I've been able to
hack together with PHP.)

Thanks much for any insights,
Alex 

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