4-5 function.php

<?php
//連線資料庫
function link_db()
{
    //實體化資料庫物件
    $mysqli = new mysqli(_DB_LOCATION, _DB_ID, _DB_PASS, _DB_NAME);
    if ($mysqli->connect_error) {
        throw new Exception('無法連上資料庫：' . $mysqli->connect_error);
    }
    $mysqli->set_charset("utf8");
    return $mysqli;
}

//檢查並傳回欲拿到資料使用的變數
function clean_var($var = '', $title = '', $filter = '')
{
    global $db;
    $clean_var = $db->real_escape_string($_REQUEST[$var]);
    if (empty($clean_var)) {
        throw new Exception("{$title}為必填！");
    }
    if ($filter) {
        $clean_var = filter_var($clean_var, $filter);
        if (!$clean_var) {
            throw new Exception("不合法的{$title}");
        }
    }
    return $clean_var;
}