基本函数

/**
* 检查邮箱是否有效
* @param $email 要检查的邮箱
* @param 返回结果
*/
function isemail($email) {
        return strlen($email) > 6 && preg_match("/^[\w\-\.]+@[\w\-\.]+(\.\w+)+$/", $email);
}

/**
* 产生随机码
* @param $length - 要多长
* @param $numberic - 数字还是字符串
* @return 返回字符串
*/
function random($length, $numeric = 0) {
        PHP_VERSION < ‘4.2.0‘ && mt_srand((double)microtime() * 1000000);
        if($numeric) {
                $hash = sprintf(‘%0‘.$length.‘d‘, mt_rand(0, pow(10, $length) - 1));
        } else {
                $hash = ‘‘;
                $chars = ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz‘;
                $max = strlen($chars) - 1;
                for($i = 0; $i < $length; $i++) {
                        $hash .= $chars[mt_rand(0, $max)];
                }
        }
        return $hash;
}

/**
* 删除非空目录
* @param $path 目录
*/
function removedir($dirname, $keepdir = FALSE) {

        $dirname = wipespecial($dirname);

        if(!is_dir($dirname)) {
                return FALSE;
        }
        $handle = opendir($dirname);
        while(($file = readdir($handle)) !== FALSE) {
                if($file != ‘.‘ && $file != ‘..‘) {
                        $dir = $dirname . DIRECTORY_SEPARATOR . $file;
                        is_dir($dir) ? removedir($dir) : unlink($dir);
                }
        }
        closedir($handle);
        return !$keepdir ? (@rmdir($dirname) ? TRUE : FALSE) : TRUE;
}

基本函数

原文：http://www.cnblogs.com/amw863/p/4846285.html