March 2022
Intermediate to advanced
522 pages
13h 52m
Chinese
Content preview from Python语言及其应用（第2版）
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日历和时钟
｜
215
13.3
使用
time
模块
令人困惑的是，
Python
有一个带有
time
对象的
datetime
模块，以及一个单独的
time
模
块。此外，
time
模块还有一个函数叫作
time()
。
表示绝对时间的一种方法是计算从某个时间起点开始的秒数。
Unix
时
间
使用自
1970
年
1
月
1
日
0
点开始的秒数。
2
这个值通常称为
纪元
（
epoch
），它是在系统之间交换日期和时间
的最简单方法。
time
模块的
time()
函数能够以纪元值的形式返回当前时间：
>>> import time
>>> now = time.time()
>>> now
1554512132.778233
自
1970
年新年以来，已经过去了
10
亿秒。那现在是什么时间？
可以使用
ctime()
将纪元值转换为字符串：
>>> time.ctime(now)
'Fri Apr 5 19:55:32 2019'
下一节会介绍如何生成更悦目的日期和时间格式。
纪元值是与不同系统（如
JavaScript
）交换日期和时间时的最小公分母
。但是有时候，你
需要的是实际的天数、小时数等，
time
以
struct_time
对象的形式给出了这些信息。
localtime()
提供了系统时区时间，而
gmtime()
提供了
UTC
（协调世界时，以前称为
格林
尼治时间
或
祖鲁时间
）：
>>> time.localtime(now)
time.struct_time(tm_year=2019, tm_mon=4, tm_mday=5, tm_hour=19,
tm_min=55, ...
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