php正则替换标签的实现方法：首先通过“strip_tags”函数剥去字符串中的HTML标签；然后利用正则表达式替换标签，代码语句如“pregreplace("/s+/","",str=pregreplace("/s+/","")”。
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1.strip_tags(剥去字符串中的 HTML 标签)
strip_tags() 函数剥去字符串中的 HTML、XML 以及 PHP 的标签。
2.字符串替换
str_replace(array(“ ”,” ”,” ”,”
”,”
”,”
”),array(“”,”“,”“,”“,”“,”“)
3.利用正则表达式(效率稍微低一些)
str=pregreplace("/s+/","",str); //过滤多余回车
str=pregreplace("/<[]+/si","<",str); //过滤<__(“<”号后面带空格)
str=pregreplace("/<??.????>/si","",str); //注释
str=pregreplace("/<(.??)>/si","",str); //过滤DOCTYPE
str=pregreplace("/<(/?html.??)>/si","",str); //过滤html标签
str=pregreplace("/<(/?head.??)>/si","",str); //过滤head标签
str=pregreplace("/<(/?meta.??)>/si","",str); //过滤meta标签
str=pregreplace("/<(/?body.??)>/si","",str); //过滤body标签
str=pregreplace("/<(/?link.??)>/si","",str); //过滤link标签
str=pregreplace("/<(/?form.??)>/si","",str); //过滤form标签
str=pregreplace("/cookie/si","COOKIE",str); //过滤COOKIE标签
str=pregreplace("/<(applet.??)>(.??)<(/applet.??)>/si","",str); //过滤applet标签
str=pregreplace("/<(/?applet.??)>/si","",str); //过滤applet标签
str=pregreplace("/<(style.??)>(.??)<(/style.??)>/si","",str); //过滤style标签
str=pregreplace("/<(/?style.??)>/si","",str); //过滤style标签
str=pregreplace("/<(title.??)>(.??)<(/title.??)>/si","",str); //过滤title标签
str=pregreplace("/<(/?title.??)>/si","",str); //过滤title标签
str=pregreplace("/<(object.??)>(.??)<(/object.??)>/si","",str); //过滤object标签
str=pregreplace("/<(/?objec.??)>/si","",str); //过滤object标签
str=pregreplace("/<(noframes.??)>(.??)<(/noframes.??)>/si","",str); //过滤noframes标签
str=pregreplace("/<(/?noframes.??)>/si","",str); //过滤noframes标签
str=pregreplace("/<(i?frame.??)>(.??)<(/i?frame.??)>/si","",str); //过滤frame标签
str=pregreplace("/<(/?i?frame.??)>/si","",str); //过滤frame标签
str=pregreplace("/<(script.??)>(.??)<(/script.??)>/si","",str); //过滤script标签
str=pregreplace("/<(/?script.??)>/si","",str); //过滤script标签
str=pregreplace("/javascript/si","Javascript",str); //过滤script标签
str=pregreplace("/vbscript/si","Vbscript",str); //过滤script标签
str=pregreplace("/on([a?z]+)s?=/si","On1=",str); //过滤script标签
str=preg_replace("/&#/si","&＃",str); //过滤script标签，如javAsCript:alert(
str=pregreplace("/<(/?.??)>/si","",str);//匹配任意html标签方式
this?>content=pregreplace("/<(/?.??)>/si","",this->content);//过滤大多数的html标签