Troubleshooting "Delimiter must not be alphanumeric or backslash" error when changing ereg() to preg_match()

Question

Possible Duplicate:
Converting ereg expressions to preg

<?php
$searchtag = "google";
$link = "http://images.google.com/images?hl=de&q=$searchtag&btnG=Bilder-Suche&gbv=1";
$code = file_get_contents($link,'r');
ereg("imgurl=http://www.[A-Za-z0-9-]*.[A-Za-z]*[^.]*.[A-Za-z]*", $code, $img);
ereg("http://(.*)", $img[0], $img_pic);
echo '<img src="'.$img_pic[0].'" width="70" height="70">'; ?> 

And i get this error

Deprecated: Function ereg() is deprecated in C:\Program Files\EasyPHP-5.3.8.1\www\m\img.php on line 5

Deprecated: Function ereg() is deprecated in C:\Program Files\EasyPHP-5.3.8.1\www\m\img.php on line 6

preg_match() functions give this error

Warning: preg_match() [function.preg-match]: Delimiter must not be alphanumeric or backslash in C:\Program Files\EasyPHP-5.3.8.1\www\m\img.php on line 6

Warning: preg_match() [function.preg-match]: Delimiter must not be alphanumeric or backslash in C:\Program Files\EasyPHP-5.3.8.1\www\m\img.php on line 7

Solution 1

1. ereg is deprecated. Don't use it.
2. The preg functions are all "Perl regular expressions" meaning you need to have some sort of beginning and end marker on your regex. Often this will be / or #, but any non alpha-numeric will do fine.

For example, these will work:

preg_match("/foo/u",$needle,$haystack);
preg_match("#foo#i",$needle,$haystack);
preg_match("@foo@",$needle,$haystack);
preg_match("\$foo\$w",$needle,$haystack); // bad idea because `$` means something
                                          // in regex but it is valid anyway
                                          // also, they need to be escaped since
                                          // I'm using " instead of '

But this will not:

preg_match("foo",$needle,$haystack); // no delimiter!

Solution 2

With preg_match() your regex must begin and end with a delimiter such as / with few exceptions (for example adding "i" at the end for case-insensative).

e.g.

preg_match('/[regex]/i', $string)