例如：判斷當前時間是否在9：00-18：00內。

    <?php
    /**
     * =======================================
     * Created by Zhihua_W.
     * Author: Zhihua_W
     * Date: 2017/6/8 0008
     * Time: 下午 18:10
     * Project: PHP開發小技巧
     * Power: PHP判斷時間在某一時間段內
     * =======================================
     */
    function get_curr_time_section()
    {
        $checkDayStr = date('Y-m-d ', time());
        $timeBegin1 = strtotime($checkDayStr . "09:00" . ":00");
        $timeEnd1 = strtotime($checkDayStr . "18:00" . ":00");
        $curr_time = time();
        if ($curr_time >= $timeBegin1 && $curr_time <= $timeEnd1) {
            return 0;
        }
        return -1;
    }
    
    $result = get_curr_time_section();
    echo $result;