在preg_match_all结果中使用str_replace

I have this code:

preg_match_all('#href="/mp3/(.*?).html#', $content, $salida);

and I need to replace "_" to " " (space) in output (array), something like this

$salida = str_replace('_', ' ', $salida);

obviously that code does not work

I think what you're looking for is preg_replace_callback

$salida = preg_replace_callback(
    '(href="/mp3/.*?\.html)',
    function($m) {return str_replace("_","",$m[0]);},
    $content);