如何删除奇怪的复制粘贴字符，如：â€

I have a php web app/tool that people end up copy-pasting data into. The data eventually turns into XML, for which certain characters produce really odd character once they are saved. I am not sure if "’" looked like that before it was copy-pasted. It might have just been interpreted that way. It might have just been a long "-". In any case, all these characters are really odd. Is there a way to strip them out easily?I have a php web app/tool that people end up co