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php中str_replace替换实例讲解

IT博客 前端开发 json 748

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详细介绍

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);
    $string = str_replace(""",""",$string);
    $string = str_replace(""","",$string);
    $string = str_replace(""","",$string);
    $string = str_replace(";","",$string);
    $string = str_replace("<","<",$string);
    $string = str_replace(">",">",$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("#<[/]{0,1}(link|meta|ifr|fra|scr)[^>]*>#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)
       {
           $text =  trim($text);
           //完全过滤注释
           $text = preg_replace("//","",$text);
           //完全过滤动态代码
           $text =  preg_replace("/<?|?".">/","",$text);
           //完全过滤js
           $text = preg_replace("//","",$text);
           $text =  str_replace("[","[",$text);
           $text = str_replace("]","]",$text);
           $text =  str_replace("|","|",$text);
           //过滤换行符
           $text = preg_replace("/ ? /","",$text);
           //br
           $text =  preg_replace("//i","[br]",$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
           $text =  preg_replace("/<(".$allowTags.")( [^><[]]*)>/i","[12]",$text);
           //过滤多余html
           if ( empty($banTag) ) { $banTag = self::$htmlTags["ban"]; }
           $text =  preg_replace("/<]*>/i","",$text);
           //过滤合法的html标签
           while(preg_match("/<([a-z]+)[^><[]]*>[^><]*/i",$text,$mat)){
               $text=str_replace($mat[0],str_replace(">","]",str_replace("<","[",$mat[0])),$text);
           }
           //转换引号
           while(preg_match("/([[^[]]*=s*)("|")([^2=[]]+)2([^[]]*])/i",$text,$mat)){
               $text=str_replace($mat[0],$mat[1]."|".$mat[3]."|".$mat[4],$text);
           }
           //空属性转换
           $text =  str_replace("""","||",$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 < >
           $text =  str_replace("<","<",$text);
           $text = str_replace(">",">",$text);
           $text = str_replace(""",""",$text);
           //反转换
           $text =  str_replace("[","<",$text);
           $text =  str_replace("]",">",$text);
           $text =  str_replace("|",""",$text);
           //过滤多余空格
           $text =  str_replace("  "," ",$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  
       // note that you have to handle splits with , , and later since they *are* 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  
       $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 
           $val = preg_replace("/(&#[xX]0{0,8}".dechex(ord($search[$i])).";?)/i", $search[$i], $val);//with a ; 
           // @ @ 0{0,7} matches "0" zero to seven times 
           $val = preg_replace("/(�{0,8}".ord($search[$i]).";?)/", $search[$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 .= "|(�{0,8}([9|10|13]);)"; 
                       $pattern .= ")*"; 
                   } 
                   $pattern .= $ra[$i][$j]; 
               } 
               $pattern .= "/i"; 
               $replacement = substr($ra[$i], 0, 2)."".substr($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 
                   $found = false; 
               } 
           } 
       } 
       return $val; 
    }
    ?>