php - preg_match_all empty matches -

i want match letter , underscore between 2 dollar signs , matches result.

example:

i <a href="$url$">foo</a> , want have url or $url$

i've tried following 2 patterns

$pattern = "/\$([a-z\_]*)\$/i"; $pattern = "/\$(.*)\$/i"; // well, that's not want. preg_match_all($pattern, $line, $matches, preg_pattern_order); 

okay should work - @ least on regex101. doesn't when test within app. empty test results

array(2) { [0]=> array(2) { [0]=> string(0) "" [1]=> string(0) "" } [1]=> array(2) { [0]=> string(0) "" [1]=> string(0) "" } }  // ... 

any ideas?

here sample text use test (i test per line)

<li>     <div class="parent">         <a href="$application_url$">             <img preview_image src="$thumbnail$">             <div class="battle_tag">$btag$</div>             <div class="class_spec">$spec_one$  /  $spec_two$ $class$</div>             <div class="item_lvl">ilvl $ilvl$</div>             <div class="date">$obtained$</div>         </a>     </div> </li> 

well since i'm not familiar php i'll post code how read actual strings too. maybe i'm doin wrong here.

$file = file($filename);  for($i=0; $i<count($file); $i++){     $line = $file[$i];     preg_match_all("/\$([a-z]*)\$/i", $line, $matches);     var_dump($matches);     echo "<br/>"; } 

use single quotes around regex:

preg_match_all('/\$([a-z]*)\$/i', $line, $matches); 

maybe better:

preg_match_all('/\$([^\$]+)\$/i', $line, $matches); 

single quotes take php out of variable interpolation mode. typically escaping $ within double quoted string enough, apparently not when double quoted string regular expression.