- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
$a = '<img alt="tXmd8xs42E0ajh_DR1nKBAfg9zsbtN0f2YXioK6zgKxsxdgJWUiAYK9R6EOOVa5AoTwnVgCqMiQVLgPkNmZ2yKaZd1kWcDfAxVvJwY_YVPXrnwsrnAnooN1qJ_GFHJSJgOaM9up4" src="https://lh3.googleusercontent.com/tXmd8xs42E0ajh_DR1nKBAfg9zsbtN0f2YXioK6zgKxsxdgJWUiAYK9R6EOOVa5AoTwnVgCqMiQVLgPkNmZ2yKaZd1kWcDfAxVvJwY_YVPXrnwsrnAnooN1qJ_GFHJSJgOaM9up4" style="border:none;width:176px;height:153px;" />';
preg_match('/src=\\"[^\\"]*\\"/', $a, $src);
var_dump($src);