$ _POST和Str_replace无法正常工作

Question

我对Str_replace有问题，他没有使用这个$ _POST方法 我想在插入mysql后替换文本字符 但是在将文本插入mysql字符后没有改变

  $news_subject = stripinput($_POST['news_subject']);

 $lt = array("ą","č","ę","į","š","ų","ū","ž"); 
 $ke = array("a","c","e","i","s","u","u","z");

 $news_url = str_replace($lt, $ke, $news_subject);