在字串與時間戳之間的相互轉換應用很廣，這裡沒考慮時區，預設的是本地時區

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# created by fhqplzj on 2017/11/14 上午9:28
import time
from datetime import datetime

time_fmt = '%Y-%m-%d %H:%M:%S'


def float_to_str(dt_float):
    return datetime.fromtimestamp(dt_float).strftime(time_fmt)


def str_to_float(dt_str):
    return time.mktime(datetime.strptime(dt_str, time_fmt).timetuple())


if __name__ == '__main__':
    s1 = '2017-10-04 23:42:17'
    s2 = '2017-08-18 05:48:13'
    f1 = str_to_float(s1)
    f2 = str_to_float(s2)
    print f1
    print f2
    s3 = float_to_str(f1)
    s4 = float_to_str(f2)
    print s3
    print s4