我也不会正则,
估计有更简单的
<?php
$str="45_192.html_3.html";
//如何显示成45_192_3
echo(preg_replace("/.html/",'',preg_replace("/(.html)_/", "_", $str)));
//上面的会显示成 45_192_3.html
//
?>
估计有更简单的
<?php
$str="45_192.html_3.html";
//如何显示成45_192_3
echo(preg_replace("/.html/",'',preg_replace("/(.html)_/", "_", $str)));
//上面的会显示成 45_192_3.html
//
?>
$str = "45_192.html_3.html";
//1
echo ( str_replace('.html', '', $str) );//2
echo ( preg_replace('[^_\d]+', '', $str) );