php中str_replace替换实例讲解

在对于字符串的替换上，我们已经学过了不少的方法。但在做练习题的时候，我们会对多个字符串进行替换。从方法的实用性来说，str_replace就非常适合处理多个字符串的替换问题。下面我们就php中str_replace的概念、语法、参数、返回值进行讲解，然后带来替换的实例分享。

1、概念

str_replace() 函数以其他字符替换字符串中的一些字符（区分大小写）。

该函数区分大小写。请使用 str_ireplace() 函数执行不区分大小写的搜索。

2、语法

str_replace(find,replace,string,count)

3、参数

Find、replace、string、count

4、返回值

返回带有替换值的字符串或数组。

5、实例

创建一个PHP示例文件；然后通过“tr_replace($vowels, "","Hello World of PHP");”方法替换多个字符串即可。

echo str_replace(array("m","i"),array("n","z"),"my name is jim!")

echo str_replace(array('m','i'),'n',"my name is jim!");

$vowels = array("a", "e", "i", "o", "u", "A", "E", "I", "O", "U");

$onlyconsonants = str_replace($vowels, "","Hello World of PHP");

echo $onlyconsonants;

知识点扩展：

PHP利用str_replace防注入的方法

   <?php

    /**

    * 安全过滤函数

    *

    * @param $string

    * @return string

    */

    function safe_replace($string) {

    $string = str_replace('%20','',$string);

    $string = str_replace('%27','',$string);

    $string = str_replace('%2527','',$string);

    $string = str_replace('*','',$string);

    $string = str_replace('"','&amp;quot;',$string);

    $string = str_replace("'",'',$string);

    $string = str_replace('"','',$string);

    $string = str_replace(';','',$string);

    $string = str_replace('&lt;','&amp;lt;',$string);

    $string = str_replace('&gt;','&amp;gt;',$string);

    $string = str_replace("{",'',$string);

    $string = str_replace('}','',$string);

    $string = str_replace('','',$string);

    return $string;

    }

    ?>

    <?php

    /**

    * 返回经addslashes处理过的字符串或数组

    * @param $string 需要处理的字符串或数组

    * @return mixed

    */

    function new_addslashes($string) {

    if(!is_array($string)) return addslashes($string);

    foreach($string as $key => $val) $string[$key] = new_addslashes($val);

    return $string;

    }

    ?>

    <?php

    //对请求的字符串进行安全处理

    /*

    $safestep

   /

/ 0 为不处理，

    1 为禁止不安全HTML内容(javascript等)，

    2 完全禁止HTML内容，并替换部份不安全字符串（如：eval(、union、CONCAT(、--、等）

    */

    function StringSafe($str, $safestep=-1){

    $safestep = ($safestep > -1) ? $safestep : 1;

    if($safestep == 1){

    $str = preg_replace("#script:#i", "ｓｃｒｉｐｔ：", $str);

    $str = preg_replace("#&lt;[/]{0,1}(link|meta|ifr|fra|scr)[^&gt;]*&gt;#isU", '', $str);

    $str = preg_replace("#[ ]{1,}#", ' ', $str);

    return $str;

    }else if($safestep == 2){

    $str = addslashes(htmlspecialchars(stripslashes($str)));

    $str = preg_replace("#eval#i", 'ｅｖａｌ', $str);

    $str = preg_replace("#union#i", 'ｕｎｉｏｎ', $str);

    $str = preg_replace("#concat#i", 'ｃｏｎｃａｔ', $str);

    $str = preg_replace("#--#", '－－', $str);

    $str = preg_replace("#[ ]{1,}#", ' ', $str);

    return $str;

    }else{

    return $str;

    }

    }

    ?>

    <?php

       /**

        +----------------------------------------------------------

        * 输出安全的html，用于过滤危险代码

        +----------------------------------------------------------

        * @access public

        +----------------------------------------------------------

        * @param string $text 要处理的字符串

        * @param mixed $tags 允许的标签列表，如 table|td|th|td

        +----------------------------------------------------------

        * @return string

        +----------------------------------------------------------

        */

       static public function safeHtml($text, $tags = null)

       {

           $text =&nbsp; trim($text);

           //完全过滤注释

           $text = preg_replace('/&lt;!--&#63;.*--&gt;/','',$text);

           //完全过滤动态代码

           $text =&nbsp; preg_replace('/&lt;&#63;|&#63;'.'&gt;/','',$text);

           //完全过滤js

           $text = preg_replace('/&lt;script&#63;.*/script&gt;/','',$text);

           $text =&nbsp; str_replace('[','&amp;#091;',$text);

           $text = str_replace(']','&amp;#093;',$text);

           $text =&nbsp; str_replace('|','&amp;#124;',$text);

           //过滤换行符

           $text = preg_replace('/ &#63; /','',$text);

           //b

           $text =&nbsp; preg_replace('/&lt;br(s/)&#63;'.'&gt;/i','[br]',$text);

           $text = preg_replace('/([br]s*){10,}/i','[br]',$text);

           //过滤危险的属性，如：过滤on事件lang js

           while(preg_match('/(<

+)(lang|on|action|background|codebase|dynsrc|lowsrc)

+/i',$text,$mat)){

               $text=str_replace($mat[0],$mat[1],$text);

           }

           while(preg_match('/(<

+)(window.|javascript:|js:|about:|file:|document.|vbs:|cookie)(

*)/i',$text,$mat)){

               $text=str_replace($mat[0],$mat[1].$mat[3],$text);

           }

           if( empty($allowTags) ) { $allowTags = self::$htmlTags['allow']; }

           //允许的HTML标签

           $text =&nbsp; preg_replace('/&lt;('.$allowTags.')(

]*)>/i','[12]',$text);

           //过滤多余html

           if ( empty($banTag) ) { $banTag = self::$htmlTags['ban']; }

           $text =&nbsp; preg_replace('/&lt;/&#63;('.$banTag.')

*>/i','',$text);

           //过滤合法的html标签

           while(preg_match('/<([a-z]+)

]

</1>/i',$text,$mat)){

               $text=str_replace($mat[0],str_replace('>',']',str_replace('<','[',$mat[0])),$text);

           }

           //转换引号

           while(preg_match('/([

]

)("|')(

]+)2(

]*])/i',$text,$mat)){

               $text=str_replace($mat[0],$mat[1].'|'.$mat[3].'|'.$mat[4],$text);

           }

           //空属性转换

           $text =&nbsp; str_replace('''','||',$text);

           $text = str_replace('""','||',$text);

           //过滤错误的单个引号

           while(preg_match('/[

]

]/i',$text,$mat)){

               $text=str_replace($mat[0],str_replace($mat[1],'',$mat[0]),$text);

           }

           //转换其它所有不合法的 < >

           $text =&nbsp; str_replace('&lt;','&amp;lt;',$text);

           $text = str_replace('&gt;','&amp;gt;',$text);

           $text = str_replace('"','&amp;quot;',$text);

           //反转换

           $text =&nbsp; str_replace('[','&lt;',$text);

           $text =&nbsp; str_replace(']','&gt;',$text);

           $text =&nbsp; str_replace('|','"',$text);

           //过滤多余空格

           $text =&nbsp; str_replace('&nbsp; ',' ',$text);

           return $text;

       }

    ?>

    <?php

    function RemoveXSS($val) {

       // remove all non-printable characters. CR(0a) and LF(0b) and TAB(9) are allowed

       // this prevents some character re-spacing such as <javascript>

       // note that you have to handle splits with , , and later since they

allowed in some          // inputs

       $val = preg_replace('/([x00-x08,x0b-x0c,x0e-x19])/', '', $val);

       // straight replacements, the user should never need these since they're normal characters

       // this prevents like <IMG SRC=@avascript:alert('XSS')>

       $search = 'abcdefghijklmnopqrstuvwxyz';

       $search .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

       $search .= '1234567890!@#$%^&*()';

       $search .= '~`";:?+/={}[]-_|'';

       for ($i = 0; $i < strlen($search); $i++) {

           // ;? matches the ;, which is optional

           // 0{0,7} matches any padded zeros, which are optional and go up to 8 chars

           // @ @ search for the hex values

           $val = preg_replace('/(&amp;#[xX]0{0,8}'.dechex(ord($search[$i])).';&#63;)/i', $search[$i], $val);//with a ;

           // @ @ 0{0,7} matches '0' zero to seven times

           $val = preg_replace('/(&amp;#0{0,8}'.ord($search[$i]).';&#63;)/', $search[$i], $val); // with a ;

       }

       // now the only remaining whitespace attacks are , , and 

       $ra1 = Array('javascript', 'vbscript', 'expression', 'applet', 'meta', 'xml', 'blink', 'link', 'style', 'script', 'embed', 'object', 'iframe', 'frame', 'frameset', 'ilayer', 'layer', 'bgsound', 'title', 'base');

       $ra2 = Array('onabort', 'onactivate', 'onafterprint', 'onafterupdate', 'onbeforeactivate', 'onbeforecopy', 'onbeforecut', 'onbeforedeactivate', 'onbeforeeditfocus', 'onbeforepaste', 'onbeforeprint', 'onbeforeunload', 'onbeforeupdate', 'onblur', 'onbounce', 'oncellchange', 'onchange', 'onclick', 'oncontextmenu', 'oncontrolselect', 'oncopy', 'oncut', 'ondataavailable', 'ondatasetchanged', 'ondatasetcomplete', 'ondblclick', 'ondeactivate', 'ondrag', 'ondragend', 'ondragenter', 'ondragleave', 'ondragover', 'ondragstart', 'ondrop', 'onerror', 'onerrorupdate', 'onfilterchange', 'onfinish', 'onfocus', 'onfocusin', 'onfocusout', 'onhelp', 'onkeydown', 'onkeypress', 'onkeyup', 'onlayoutcomplete', 'onload', 'onlosecapture', 'onmousedown', 'onmouseenter', 'onmouseleave', 'onmousemove', 'onmouseout', 'onmouseover', 'onmouseup', 'onmousewheel', 'onmove', 'onmoveend', 'onmovestart', 'onpaste', 'onpropertychange', 'onreadystatechange', 'onreset', 'onresize', 'onresizeend', 'onresizestart', 'onrowenter', 'onrowexit', 'onrowsdelete', 'onrowsinserted', 'onscroll', 'onselect', 'onselectionchange', 'onselectstart', 'onstart', 'onstop', 'onsubmit', 'onunload');

       $ra = array_merge($ra1, $ra2);

       $found = true; // keep replacing as long as the previous round replaced something

       while ($found == true) {

           $val_before = $val;

           for ($i = 0; $i < sizeof($ra); $i++) {

               $pattern = '/';

               for ($j = 0; $j < strlen($ra[$i]); $j++) {

                   if ($j > 0) {

                       $pattern .= '(';

                       $pattern .= '(&#[xX]0{0,8}([9ab]);)';

                       $pattern .= '|';

                       $pattern .= '|(&#0{0,8}([9|10|13]);)';

                       $pattern .= ')*';

                   }

                   $pattern .= $ra[$i][$j];

               }

               $pattern .= '/i';

               $replacement = substr($ra[$i], 0, 2).'&lt;x&gt;'.substr($ra[$i], 2); // add in <> to nerf the tag

               $val = preg_replace($pattern, $replacement, $val); // filter out the hex tags

               if ($val_before == $val) {

                   // no replacements were made, so exit the loop

      &n/

/bsp;            $found = false;

               }

           }

       }

       return $val;

    }

    ?>