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本节大纲：
一、模块介绍：
模块，用一砣代码实现了某个功能的代码集合。
类似于函数式编程和面向过程编程，函数式编程则完成一个功能，其他代码用来调用即可，提供了代码的重用性和代码间的耦合。而对于一个复杂的功能来，可能需要多个函数才能完成
（函数又可以在不同的.py文件中），n个 .py 文件组成的代码集合就称为模块。
如：os 是系统相关的模块；file是文件操作相关的模块
模块分为三种：
①自定义模块
②内置标准模块（又称标准库）
③开源模块
二、time &datetime模块
1 import time
2 import datetime
3
4 print(time.clock()) #返回处理器时间,3.3开始已废弃
5 print(time.process_time()) #返回处理器时间,3.3开始已废弃
6 print(time.time()) #返回当前系统时间戳
7 print(time.ctime()) #输出Tue Jan 26 18:23:48 2016 ,当前系统时间
8 print(time.ctime(time.time()-86640)) #将时间戳转为字符串格式
9 print(time.gmtime(time.time()-86640)) #将时间戳转换成struct_time格式
10 print(time.localtime(time.time()-86640)) #将时间戳转换成struct_time格式,但返回 的本地时间
11 print(time.mktime(time.localtime())) #与time.localtime()功能相反,将struct_time格式转回成时间戳格式
12 #time.sleep(4) #sleep
13 print(time.strftime("%Y-%m-%d %H:%M:%S",time.gmtime()) ) #将struct_time格式转成指定的字符串格式
14 print(time.strptime("2016-01-28","%Y-%m-%d") ) #将字符串格式转换成struct_time格式
15
16 #datetime module
17
18 print(datetime.date.today()) #输出格式 2016-01-26
19 print(datetime.date.fromtimestamp(time.time()-864400) ) #2016-01-16 将时间戳转成日期格式
20 current_time = datetime.datetime.now() #
21 print(current_time) #输出2016-01-26 19:04:30.335935
22 print(current_time.timetuple()) #返回struct_time格式
23
24 #datetime.replace([year[, month[, day[, hour[, minute[, second[, microsecond[, tzinfo]]]]]]]])
25 print(current_time.replace(2014,9,12)) #输出2014-09-12 19:06:24.074900,返回当前时间,但指定的值将被替换
26
27 str_to_date = datetime.datetime.strptime("21/11/06 16:30", "%d/%m/%y %H:%M") #将字符串转换成日期格式
28 new_date = datetime.datetime.now() + datetime.timedelta(days=10) #比现在加10天
29 new_date = datetime.datetime.now() + datetime.timedelta(days=-10) #比现在减10天
30 new_date = datetime.datetime.now() + datetime.timedelta(hours=-10) #比现在减10小时
31 new_date = datetime.datetime.now() + datetime.timedelta(seconds=120) #比现在+120s
32 print(new_date)
格式如下表格：
| Directive | Meaning | Notes |
|---|---|---|
%a |
Locale’s abbreviated weekday name. | |
%A |
Locale’s full weekday name. | |
%b |
Locale’s abbreviated month name. | |
%B |
Locale’s full month name. | |
%c |
Locale’s appropriate date and time representation. | |
%d |
Day of the month as a decimal number [01,31]. | |
%H |
Hour (24-hour clock) as a decimal number [00,23]. | |
%I |
Hour (12-hour clock) as a decimal number [01,12]. | |
%j |
Day of the year as a decimal number [001,366]. | |
%m |
Month as a decimal number [01,12]. | |
%M |
Minute as a decimal number [00,59]. | |
%p |
Locale’s equivalent of either AM or PM. | (1) |
%S |
Second as a decimal number [00,61]. | (2) |
%U |
Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0. |
(3) |
%w |
Weekday as a decimal number [0(Sunday),6]. | |
%W |
Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0. |
(3) |
%x |
Locale’s appropriate date representation. | |
%X |
Locale’s appropriate time representation. | |
%y |
Year without century as a decimal number [00,99]. | |
%Y |
Year with century as a decimal number. | |
%z |
Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM, where H represents decimal hour digits and M represents decimal minute digits [-23:59, +23:59]. |
|
%Z |
Time zone name (no characters if no time zone exists). | |
%% |
A literal ‘%‘ character. |
二、random模块
1、随机数
eg:
1 import random 2 print random.random() 3 print random.randint(1,2) 4 print random.randrange(1,10)
2、生成随机验证码
eg：
1 import random 2 checkcode = ‘‘ 3 for i in range(4): 4 current = random.randrange(0,4) 5 if current != i: 6 temp = chr(random.randint(65,90)) 7 else: 8 temp = random.randint(0,9) 9 checkcode += str(temp) 10 print checkcode
Python 常用模块之time&datetime 和random
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原文地址：http://www.cnblogs.com/zhangqigao/p/5498597.html
