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php中str_replace替换实例讲解

转载 作者：qq735679552 更新时间：2022-09-27 22:32:09 25 4
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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

?
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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.

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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 。

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    <?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 ( '"' , '&quot;' , $string );
     $string = str_replace ( "'" ,'', $string );
     $string = str_replace ( '"' , '' , $string );
     $string = str_replace ( ';' , '' , $string );
     $string = str_replace ( '<' , '&lt;' , $string );
     $string = str_replace ( '>' , '&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( "#<[/]{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( '/<script?.*/script>/' , '' , $text );
            $text =  str_replace ( '[' , '&#091;' , $text );
            $text = str_replace ( ']' , '&#093;' , $text );
            $text =  str_replace ( '|' , '&#124;' , $text );
            //过滤换行符
            $text = preg_replace( '/ ? /' , '' , $text );
            //br
            $text =  preg_replace( '/<br(s/)?' . '>/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( '/</?(' . $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( '/([[^[]]*=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 ( '<' , '&lt;' , $text );
            $text = str_replace ( '>' , '&gt;' , $text );
            $text = str_replace ( '"' , '&quot;' , $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 <javascript>
        // 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 <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( '/(&#[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{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{0,8}([9|10|13]);)' ;
                        $pattern .= ')*' ;
                    }
                    $pattern .= $ra [ $i ][ $j ];
                }
                $pattern .= '/i' ;
                $replacement = substr ( $ra [ $i ], 0, 2). '<x>' . 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 ;
     }
     ?>

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