- preg_match: documentation ( source)
- print_r: documentation ( source)
- addslashes: documentation ( source)
<?php
$sbj = addslashes(striptags('<iframe width="100%" height="450" scrolling="no" frameborder="no" src="https://w.soundcloud.com/player/?url=https%3A//api.soundcloud.com/tracks/145834350&auto_play=false&hide_related=false&show_comments=true&show_user=true&show_reposts=false&visual=true"></iframe>'));
$ptrn = 'src="([^"]+)';
preg_match($sbj, $ptrn, $match);
print_r($match);