$re = '/("images)/';
$str = '.ui-widget-content {
border: 1px solid #aaaaaa;
background: #ffffff url("images/ui-bg_flat_75_ffffff_40x100.png") 50% 50% repeat-x;
color: #222222;
}
.ui-widget-content a {
color: #222222;
}
.ui-widget-header {
border: 1px solid #aaaaaa;
background: #cccccc url("images/ui-bg_highlight-soft_75_cccccc_1x100.png") 50% 50% repeat-x;
color: #222222;
font-weight: bold;
}';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php