这篇文章主要介绍了php中str_replace替换实例讲解内容，有需要的朋友们可以学习参考下。
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 $string;}?><?php//对请求的字符串进行安全处理/*$safestep0 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]',$text);//过滤危险的属性，如：过滤on事件lang jswhile(preg_match('/(<[^><]+)(lang|on|action|background|codebase|dynsrc|lowsrc)[^><]+/i',$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]',$text);//过滤多余htmlif ( empty($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 < >$text = str_replace('<','<',$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 $text;}?><?phpfunction RemoveXSS($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 somethingwhile ($found == true) {$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, $val); // filter out the hex tagsif ($val_before == $val) {// no replacements were made, so exit the loop$found = false;}}}return $val;}?>
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