php中str_replace替换实例讲解
发布:smiling 来源: PHP粉丝网 添加日期:2022-04-12 08:37:39 浏览: 评论:0
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
- $text = preg_replace('/<script?.*/script>/','',$text);
- $text = str_replace('[','[',$text);
- $text = str_replace(']',']',$text);
- $text = str_replace('|','|',$text);
- //过滤换行符
- $text = preg_replace('/ ? /','',$text);
- //br
- $text = preg_replace('/<br(s/)?'.'>/i','[br]',$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],$text);
- }
- if( emptyempty($allowTags) ) { $allowTags = self::$htmlTags['allow']; }
- //允许的HTML标签
- $text = preg_replace('/<('.$allowTags.')( [^><[]]*)>/i','[12]',$text);
- //过滤多余html
- if ( emptyempty($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 < >
- $text = str_replace('<','<',$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 <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
- $val = preg_replace('/(�{0,8}'.ord($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[$i], 0, 2).'<x>'.substr($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;
- }
- ?>
Tags: str_replace
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