How to clear html code in php

php清除html代码的方法：1、通过“strip_tags($str)”去掉HTML及PHP的标记；2、通过htmlspecialchars把html中的标签转换为html实体；3、通过正则表达式过滤css等样式。

本文操作环境：windows7系统、PHP7.1版，DELL G3电脑

php中去除文字内容中所有html代码

PHP已经为我们提供了很多清除html格式的方法了，下面就让老高介绍一下。

I. strip_tags

strip_tags($str) 去掉 HTML 及 PHP 的标记

语法: string strip_tags(string str);

传回值: 字串

函式种类: 资料处理

内容说明 :

解析：本函式可去掉字串中包含的任何 HTML 及 PHP 的标记字串。若是字串的 HTML 及 PHP 标签原来就有错，例如少了大于的符号，则也会传回错误。这个函数和 fgetss() 有着相同的功能

例子

echo strip_tags("Hello world!");
# Hello world!

II. htmlspecialchars

这个函数把html中的标签转换为html实体，博客的代码展示就必须使用这个函数，要不贴出来的代码就会被执行了。

预定义的字符是：

& （和号） 成为 &
” （双引号） 成为 ”
‘ （单引号） 成为 ‘
< （小于） 成为 < > （大于） 成为 >

例子

$new = htmlspecialchars("Test", ENT_QUOTES);
echo $new; 
# <a href=&#39;test&#39;>Test</a>
# 如果需要展现
，那么浏览器解析HTML的时候会自动将他变为换行
# 但是通过htmlspecialchars就可以让< 变为 &#39;

与htmlspecialchars功能相反的函数是htmlspecialchars_decode，他会把HTML实体转化为字符！

【推荐学习：《PHP视频教程》】

III. 后补函数

PHP去除html、css样式、js格式的方法很多，但发现，它们基本都有一个弊端：空格往往清除不了

经过不断的研究，最终找到了一个理想的去除html包括空格css样式、js 的PHP函数。

$descclear = str_replace("\r","",$descclear);//过滤换行
$descclear = str_replace("\n","",$descclear);//过滤换行
$descclear = str_replace("\t","",$descclear);//过滤换行
$descclear = str_replace("\r\n","",$descclear);//过滤换行
$descclear = preg_replace("/\s+/", " ", $descclear);//过滤多余回车
$descclear = preg_replace("/<[ ]+/si","<",$descclear); //过滤<__("<"号后面带空格)
$descclear = preg_replace("/<\!--.*?-->/si","",$descclear); //过滤html注释
$descclear = preg_replace("/<(\!.*?)>/si","",$descclear); //过滤DOCTYPE
$descclear = preg_replace("/<(\/?html.*?)>/si","",$descclear); //过滤html标签
$descclear = preg_replace("/<(\/?head.*?)>/si","",$descclear); //过滤head标签
$descclear = preg_replace("/<(\/?meta.*?)>/si","",$descclear); //过滤meta标签
$descclear = preg_replace("/<(\/?body.*?)>/si","",$descclear); //过滤body标签
$descclear = preg_replace("/<(\/?link.*?)>/si","",$descclear); //过滤link标签
$descclear = preg_replace("/<(\/?form.*?)>/si","",$descclear); //过滤form标签
$descclear = preg_replace("/cookie/si","COOKIE",$descclear); //过滤COOKIE标签
$descclear = preg_replace("/<(applet.*?)>(.*?)<(\/applet.*?)>/si","",$descclear); //过滤applet标签
$descclear = preg_replace("/<(\/?applet.*?)>/si","",$descclear); //过滤applet标签
$descclear = preg_replace("/<(style.*?)>(.*?)<(\/style.*?)>/si","",$descclear); //过滤style标签
$descclear = preg_replace("/<(\/?style.*?)>/si","",$descclear); //过滤style标签
$descclear = preg_replace("/<(title.*?)>(.*?)<(\/title.*?)>/si","",$descclear); //过滤title标签
$descclear = preg_replace("/<(\/?title.*?)>/si","",$descclear); //过滤title标签
$descclear = preg_replace("/<(object.*?)>(.*?)<(\/object.*?)>/si","",$descclear); //过滤object标签
$descclear = preg_replace("/<(\/?objec.*?)>/si","",$descclear); //过滤object标签
$descclear = preg_replace("/<(noframes.*?)>(.*?)<(\/noframes.*?)>/si","",$descclear); //过滤noframes标签
$descclear = preg_replace("/<(\/?noframes.*?)>/si","",$descclear); //过滤noframes标签
$descclear = preg_replace("/<(i?frame.*?)>(.*?)<(\/i?frame.*?)>/si","",$descclear); //过滤frame标签
$descclear = preg_replace("/<(\/?i?frame.*?)>/si","",$descclear); //过滤frame标签
$descclear = preg_replace("/<(script.*?)>(.*?)<(\/script.*?)>/si","",$descclear); //过滤script标签
$descclear = preg_replace("/<(\/?script.*?)>/si","",$descclear); //过滤script标签
$descclear = preg_replace("/javascript/si","Javascript",$descclear); //过滤script标签
$descclear = preg_replace("/vbscript/si","Vbscript",$descclear); //过滤script标签
$descclear = preg_replace("/on([a-z]+)\s*=/si","On\\1=",$descclear); //过滤script标签
$descclear = preg_replace("/

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