regex - PHP preg_replace string with value of variable -

i trying use regex in php find strings starts "$" , replacing appropriate variable. example:

$value = "some value"; <b>$value</b> 

where end result should be:

<b>some value</b> 

this have tried:

ob_start("tagreplace");   function tagreplace ( $tagreplace )  {      $value1 = "some value";     $pattern = '/(?<=\s)(\$[^#\s]+)(?=\s)/';      $tagreplace = preg_replace( $pattern , '<?php echo $0 ?>', $tagreplace);      return $tagreplace; }  /* html files combining */ include 'main_content.html';  ob_end_flush(); 

but doesn't seem work... i've tried loops, while loops, , none of them working. trying extremely lazy , use regex make shorthand variables can put everywhere, replacing strings "$value" whatever corresponding value variable $value has assigned it.

i understand /e deprecated can't use treat php tags actual code. have attempted use preg_replace_callback didn't anything. i'm thinking there isn't way this.

it's not clear you're trying here, although if take different approach regex you'll have more success. it's easier break pattern 3 capture groups (the start tag, value, , end tag)

function tagreplace ( $tagreplace ) {      $replace = "some value";     $pattern = '/(.+>)(.+)(<.+)/m';     $tagreplace = preg_replace( $pattern, '$1'.$replace.'$3', $tagreplace);     return $tagreplace; }  $value = "old value"; echo tagreplace("<b>$value</b>");  echo "\n -- using \$value different-- \n";  $value = "<b>$value</b>"; echo tagreplace($value); 

by using more generic pattern should able swap out $value, regardless if it's entire value, or if it's between < > tags. when in doubt use regex tester (linked below) , might able eliminate several recursive loops, or going around in circles.

example:

https://regex101.com/r/rw8lc6/1