HTML代码中的表单如下所示：

<form method="get" id="searchform" action="<?php echo $_SERVER[\'PHP_SELF\']; ?>">
    <label class="hidden" for="s"><?php _e(\'Search this site:\'); ?></label>
    <input type="text" value="Search site" name="s" id="s" />
    <input type="submit" id="searchsubmit" value="Search" />
</form>

PHp在这个片段中没有被解析，所以我猜您没有包含PHp文件，只有普通的HTML。将搜索表单代码放入PHP文件中。

例如，您可以将这样的函数添加到functions.php:

function t5_search_form( $args = array () )
{
    $defaults = array (
        \'form_id\'  => \'searchform\',
        \'name\'     => \'s\',
        \'charset\'  => get_bloginfo( \'charset\' ),
        \'label\'    => esc_attr__( \'Search\', \'t5_theme\' ),
        \'action\'   => site_url(),
        \'value\'    => esc_attr(
            apply_filters( \'the_search_query\', get_search_query( FALSE ) )
        ),
        \'submit\'   => esc_attr__( \'Search\', \'t5_theme\' ),
        \'template\' => \'
        <form role="search" id="%1$s" accept-charset="%2$s" action="%8$s">
        <label for="%3$s">%4$s</label>
        <input type="search" name="%3$s" id="%3$s" value="%5$s" aria-required="true" required%6$s>
        <input type="submit" value="%7$s">
        </form>\',
        \'print\' => TRUE
    );

    $options = array_merge( $defaults, $args );
    $options = apply_filters( \'t5_searchform\', $options );
    extract( $options );
    $autofocus = ( is_search() and 0 === (int) $GLOBALS["wp_query"]->found_posts )
    ? \' autofocus\' : \'\';

    $form = sprintf(
        $template,
        $form_id,
        $charset,
        $name,
        $label,
        $value,
        $autofocus,
        $submit,
        $action
    );

    $print and print $form;
    return $form;
}

…并在需要时调用该函数t5_search_form();.

另外，不要使用$_SERVER[\'PHP_SELF\'];, 使用echo home_url(); 相反