PHP学习：分享自定义的几个PHP功能函数

function filter($text)
{
 //完全过滤注释
 $text = preg_replace('/<!--?.*-->/', '', $text);
 //完全过滤js
 $text = preg_replace('/<script?.*\/script>/', '', $text);
 //过滤危险的属性,如：过滤on事件lang js
 while (preg_match('/(<[^><]+)( lang|action|background|codebase|dynsrc|lowsrc)[^><]+/i', $text, $mat)) {
 $text = str_replace($mat[0], $mat[1], $text);
 }
 while (preg_match('/(<[^><]+)(window\.||js:|about:|file:|document\.|vbs:|cookie)([^><]*)/i', $text, $mat)) {
 $text = str_replace($mat[0], $mat[1] . $mat[3], $text);
 }
 //过滤多余html
 $text = preg_replace('/<\/?(html|head|meta|link|base|basefont|body|bgsound|script|form|iframe|frame|frameset|applet|id|ilayer|layer|name|script|xml)[^><]*>/i', '', $text);
 //反转换
 $text = str_replace('[', '<', $text);
 $text = str_replace(']', '>', $text);
 $text = str_replace('|', '"', $text);
 return $text;
}

function stripslashes_array(&$array)
{
 while (list($key, $var) = each($array)) {
 if ($key != 'argc' && $key != 'argv' && (strtoupper($key) != $key || '' . intval($key) == "$key")) {
 if (is_string($var)) {
 $array[$key] = stripslashes($var);
 }
 if (is_array($var)) {
 $array[$key] = stripslashes_array($var);
 }
 }
 }
 return $array;
}

function subString($strings, $start, $length)
{
 if (function_exists('mb_substr') && function_exists('mb_strlen')) {
 $sub_str = mb_substr($strings, $start, $length, 'utf8');
 return mb_strlen($sub_str, 'utf8') < mb_strlen($strings, 'utf8') ? $sub_str . '...' : $sub_str;
 }
 $str = substr($strings, $start, $length);
 $char = 0;
 for ($i = 0; $i < strlen($str); $i++) {
 if (ord($str[$i]) >= 128)
 $char++;
 }
 $str2 = substr($strings, $start, $length + 1);
 $str3 = substr($strings, $start, $length + 2);
 if ($char % 3 == 1) {
 if ($length <= strlen($strings)) {
 $str3 = $str3 .= '...';
 }
 return $str3;
 }
 if ($char % 3 == 2) {
 if ($length <= strlen($strings)) {
 $str2 = $str2 .= '...';
 }
 return $str2;
 }
 if ($char % 3 == 0) {
 if ($length <= strlen($strings)) {
 $str = $str .= '...';
 }
 return $str;
 }
}

function AnonymousIP() 
{
 $ip = GetIP();
 if ($ip == "Unknown") {
 $removed_ip = "未知用户";
 }
 if (strpos($ip, ":")) {
 $removed_ip = "IPv6用户";
 } else {
 $reg1 = '/((?:\d+\.){3})\d+/';
 $reg2 = '~(\d+)\.(\d+)\.(\d+)\.(\d+)~';
 $removed_ip = preg_replace($reg1, "\\1*", $ip);
 }
 return $removed_ip;
}

function GetIP()
{
 if (@$_SERVER["HTTP_X_FORWARDED_FOR"])
 $ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
 else if (@$_SERVER["HTTP_CLIENT_IP"])
 $ip = $_SERVER["HTTP_CLIENT_IP"];
 else if (@$_SERVER["REMOTE_ADDR"])
 $ip = $_SERVER["REMOTE_ADDR"];
 else if (@getenv("HTTP_X_FORWARDED_FOR"))
 $ip = getenv("HTTP_X_FORWARDED_FOR");
 else if (@getenv("HTTP_CLIENT_IP"))
 $ip = getenv("HTTP_CLIENT_IP");
 else if (@getenv("REMOTE_ADDR"))
 $ip = getenv("REMOTE_ADDR");
 else
 $ip = "Unknown";
 return $ip;
}

function dencrypt($string, $isEncrypt = true, $key = "youdian")
{
 if (!isset($string{0}) || !isset($key{0})) {
 return false;
 }
 
 $dynKey = $isEncrypt ? hash('sha1', microtime(true)) : substr($string, 0, 40);
 $fixedKey = hash('sha1', $key);
 
 $dynKeyPart1 = substr($dynKey, 0, 20);
 $dynKeyPart2 = substr($dynKey, 20);
 $fixedKeyPart1 = substr($fixedKey, 0, 20);
 $fixedKeyPart2 = substr($fixedKey, 20);
 $key = hash('sha1', $dynKeyPart1 . $fixedKeyPart1 . $dynKeyPart2 . $fixedKeyPart2);
 
 $string = $isEncrypt ? $fixedKeyPart1 . $string . $dynKeyPart2 : (isset($string{339}) ? gzuncompress(base64_decode(substr($string, 40))) : base64_decode(substr($string, 40)));
 
 $n = 0;
 $result = '';
 $len = strlen($string);
 
 for ($n = 0; $n < $len; $n++) {
 $result .= chr(ord($string{$n}) ^ ord($key{$n % 40}));
 }
 return $isEncrypt ? $dynKey . str_replace('=', '', base64_encode($n > 299 ? gzcompress($result) : $result)) : substr($result, 20, -20);
}

function CheckChinese($string)
{
 if (preg_match("/[\x7f-\xff]/", $string)) {
 return true;
 } else {
 return false;
 }
}

function FileHeaderJump($file)
{
 header('Content-Description: File Transfer');
 header('Content-Type: application/octet-stream');
 header('Content-Disposition: attachment; filename=' . basename($file));
 header('Content-Transfer-Encoding: binary');
 header('Expires: 0');
 header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
 header('Pragma: public');
 header('Content-Length: ' . filesize($file));
 ob_clean();
 flush();
 readfile($file);
 exit;
}

function CreateRandomString($length)
{
 $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
 $password = "";
 for ($i = 0; $i < $length; $i++) {
 $password .= $chars[mt_rand(0, strlen($chars) - 1)];
 }
 return $password;
}