收集整理的非常有用的PHP函数

<?php
//加密解密
function encryptDecrypt($key, $string, $decrypt){
    if($decrypt){
        $decrypted = rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode($string), MCRYPT_MODE_CBC, md5(md5($key))), "12");
        return $decrypted;
    }else{
        $encrypted = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), $string, MCRYPT_MODE_CBC, md5(md5($key))));
        return $encrypted;
    }
}

//生成随机字符串
function generateRandomString($length = 10) {
    $characters = ‘0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ‘;
    $randomString = ‘‘;
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, strlen($characters) - 1)];
    }
    return $randomString;
}
//获取文件扩展名
function getExtension($filename){
  $myext = substr($filename, strrpos($filename, ‘.‘));
  return str_replace(‘.‘,‘‘,$myext);
}

//获取文件大小并格式化
function formatSize($size) {
    $sizes = array(" Bytes", " KB", " MB", " GB", " TB", " PB", " EB", " ZB", " YB");
    if ($size == 0) { 
        return(‘n/a‘); 
    } else {
      return (round($size/pow(1024, ($i = floor(log($size, 1024)))), 2) . $sizes[$i]); 
    }
}

//PHP替换标签字符
function stringParser($string,$replacer){
    $result = str_replace(array_keys($replacer), array_values($replacer),$string);
    return $result;
}

//列出目录下的文件
function listDirFiles($DirPath){
    if($dir = opendir($DirPath)){
         while(($file = readdir($dir))!== false){
                if(!is_dir($DirPath.$file))
                {
                    echo "filename: $file<br />";
                }
         }
    }
}

//获取当前页面的url
function curPageURL() {
    $pageURL = ‘http‘;
    if (!empty($_SERVER[‘HTTPS‘])) {$pageURL .= "s";}
    $pageURL .= "://";
    if ($_SERVER["SERVER_PORT"] != "80") {
        $pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
    } else {
        $pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
    }
    return $pageURL;
}

//强制下载
function download($filename){
    if ((isset($filename))&&(file_exists($filename))){
       header("Content-length: ".filesize($filename));
       header(‘Content-Type: application/octet-stream‘);
       header(‘Content-Disposition: attachment; filename="‘ . $filename . ‘"‘);
       readfile("$filename");
    } else {
       echo "Looks like file does not exist!";
    }
}

/*
 Utf-8、gb2312都支持的汉字截取函数
 cut_str(字符串, 截取长度, 开始长度, 编码);
 编码默认为 utf-8
 开始长度默认为 0
*/
function cutStr($string, $sublen, $start = 0, $code = ‘UTF-8‘){
    if($code == ‘UTF-8‘){
        $pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/";
        preg_match_all($pa, $string, $t_string);

        if(count($t_string[0]) - $start > $sublen) return join(‘‘, array_slice($t_string[0], $start, $sublen))."...";
        return join(‘‘, array_slice($t_string[0], $start, $sublen));
    }else{
        $start = $start*2;
        $sublen = $sublen*2;
        $strlen = strlen($string);
        $tmpstr = ‘‘;

        for($i=0; $i<$strlen; $i++){
            if($i>=$start && $i<($start+$sublen)){
                if(ord(substr($string, $i, 1))>129){
                    $tmpstr.= substr($string, $i, 2);
                }else{
                    $tmpstr.= substr($string, $i, 1);
                }
            }
            if(ord(substr($string, $i, 1))>129) $i++;
        }
        if(strlen($tmpstr)<$strlen ) $tmpstr.= "...";
        return $tmpstr;
    }
}


//获取用户真实IP
function getIp() {
    if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))
        $ip = getenv("HTTP_CLIENT_IP");
    else
        if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))
            $ip = getenv("HTTP_X_FORWARDED_FOR");
        else
            if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))
                $ip = getenv("REMOTE_ADDR");
            else
                if (isset ($_SERVER[‘REMOTE_ADDR‘]) && $_SERVER[‘REMOTE_ADDR‘] && strcasecmp($_SERVER[‘REMOTE_ADDR‘], "unknown"))
                    $ip = $_SERVER[‘REMOTE_ADDR‘];
                else
                    $ip = "unknown";
    return ($ip);
}

//防止注入
function injCheck($sql_str) { 
    $check = preg_match(‘/select|insert|update|delete|\‘|\/\*|\*|\.\.\/|\.\/|union|into|load_file|outfile/‘, $sql_str);
    if ($check) {
        echo ‘非法字符！！‘.$sql_str;
        exit;
    } else {
        return $sql_str;
    }
}

//页面提示跳转
function message($msgTitle,$message,$jumpUrl){
    $str = ‘<!DOCTYPE HTML>‘;
    $str .= ‘<html>‘;
    $str .= ‘<head>‘;
    $str .= ‘<meta charset="utf-8">‘;
    $str .= ‘<title>页面提示</title>‘;
    $str .= ‘<style type="text/css">‘;
    $str .= ‘*{margin:0; padding:0}a{color:#369; text-decoration:none;}a:hover{text-decoration:underline}body{height:100%; font:12px/18px Tahoma, Arial,  sans-serif; color:#424242; background:#fff}.message{width:450px; height:120px; margin:16% auto; border:1px solid #99b1c4; background:#ecf7fb}.message h3{height:28px; line-height:28px; background:#2c91c6; text-align:center; color:#fff; font-size:14px}.msg_txt{padding:10px; margin-top:8px}.msg_txt h4{line-height:26px; font-size:14px}.msg_txt h4.red{color:#f30}.msg_txt p{line-height:22px}‘;
    $str .= ‘</style>‘;
    $str .= ‘</head>‘;
    $str .= ‘<body>‘;
    $str .= ‘<div class="message">‘;
    $str .= ‘<h3>‘.$msgTitle.‘</h3>‘;
    $str .= ‘<div class="msg_txt">‘;
    $str .= ‘<h4 class="red">‘.$message.‘</h4>‘;
    $str .= ‘<p>系统将在 <span style="color:blue;font-weight:bold">3</span> 秒后自动跳转,如果不想等待,直接点击 <a href="{$jumpUrl}">这里</a> 跳转</p>‘;
    $str .= "<script>setTimeout(‘location.replace(\‘".$jumpUrl."\‘)‘,2000)</script>";
    $str .= ‘</div>‘;
    $str .= ‘</div>‘;
    $str .= ‘</body>‘;
    $str .= ‘</html>‘;
    echo $str;
}


//时间长度转换
function changeTimeType($seconds) {
    if ($seconds > 3600) {
        $hours = intval($seconds / 3600);
        $minutes = $seconds % 3600;
        $time = $hours . ":" . gmstrftime(‘%M:%S‘, $minutes);
    } else {
        $time = gmstrftime(‘%H:%M:%S‘, $seconds);
    }
    return $time;
}


?>