str_replace 将弄乱页面上任何不吉利的标记，因为它将替换标记或URL内的匹配文本。

你想要的是我给另一个问题的答案的修改版本about highlighting search terms. 变化将是highlight_search_term 作用您只需将其更改为使用$_GET 数据而不是搜索数据。

function highlight_search_term($text){
  if(!empty($_GET[\'city\']){
    $keys = strip_tags($_GET[\'city\']); // nominal validation
    $pattern = \'/<[^>].*?>/i\';
    preg_match_all($pattern,$text,$matches);
    $placeholders = array();
    foreach ($matches[0] as $v) {
      $placeholders[] = highlight_search_term_placeholders();
    }
    $text = preg_replace_callback($pattern,\'highlight_search_term_cb\',$text);
    $pattern2 = \'/(\' . $keys .\')/iu\';
    $text = preg_replace($pattern2, \' <span class="search-term">\\1</span> \', $text);
    $text = preg_replace($placeholders,$matches[0],$text);
  }
  return $text;
}