php 如果在本页面提交表单，如何记住radio单选框的值

代码如下：

<form method=\"post\">
<input type=\"radio\" name=\"radio\" value=\"yes\" class=\"radio\" <?php if (isset($_POST[\'radio\']) && $_POST[\'radio\'] == \'yes\'): ?>checked=\'checked\'<?php endif; ?> /> Yes
<input type=\"radio\" name=\"radio\" value=\"no\"  class=\"radio\" <?php if (isset($_POST[\'radio\']) && $_POST[\'radio\'] ==  \'no\'): ?>checked=\'checked\'<?php endif; ?> /> No
<input type=\"submit\" name=\"submit\" value=\"提交\" />
</form>