常用功能函数

// 随机字符串
function random($length, $numeric = FALSE) {
    $seed = base_convert(md5(microtime() . $_SERVER['DOCUMENT_ROOT']), 16, $numeric ? 10 : 35);
    $seed = $numeric ? (str_replace('0', '', $seed) . '012340567890') : ($seed . 'zZ' . strtoupper($seed));
    if ($numeric) {
        $hash = '';
    } else {
        $hash = chr(rand(1, 26) + rand(0, 1) * 32 + 64);
        $length--;
    }
    $max = strlen($seed) - 1;
    for ($i = 0; $i < $length; $i++) {
        $hash .= $seed{mt_rand(0, $max)};
    }
    return $hash;
}

// 单位转化
function sizecount($size) {
    if($size >= 1073741824) {
        $size = round($size / 1073741824 * 100) / 100 . ' GB';
    } elseif($size >= 1048576) {
        $size = round($size / 1048576 * 100) / 100 . ' MB';
    } elseif($size >= 1024) {
        $size = round($size / 1024 * 100) / 100 . ' KB';
    } else {
        $size = $size . ' Bytes';
    }
    return $size;
}