Python strftime() function is present in datetime and time modules to create a string representation based on the specified format string.

datetime和time模块中提供了Python strftime（）函数，用于基于指定的格式字符串创建字符串表示形式。

Python strftime（） (Python strftime())

• Python datetime module strftime() function and time module strftime() function behaves exactly the same. However, their syntax is slightly different.

  Python datetime module strftime() function syntax is:

  datetime_object.strftime(format_str)

  Python time module strftime() function syntax is:

  This function converts a tuple or struct_time object to a string as specified by the format argument. If ‘time_object’ is not provided, the current time as returned by localtime() is used. The format argument must be a string.

  Python datetime模块 strftime（）函数的语法为：

  datetime_object.strftime(format_str)

  Python时间模块 strftime（）函数的语法为：

  此函数将元组或struct_time对象转换为format参数指定的字符串。 如果未提供“ time_object”，则使用localtime（）返回的当前时间。 format参数必须是字符串。

• For time objects (datetime.time()), the format codes for the year, month, and day should not be used, as time objects have no such values. If they’re used anyway, 1900 is substituted for the year, and 1 for the month and day.对于时间对象（datetime.time（）），不应使用年，月和日的格式代码，因为时间对象没有此类值。 如果仍然使用它们，则用1900代替年份，用1代替月份和日期。
• For date objects (datetime.date()), the format codes for hours, minutes, seconds, and microseconds should not be used, as date objects have no such values. If they’re used anyway, 0 is substituted for them.对于日期对象（datetime.date（）），不应使用小时，分钟，秒和微秒的格式代码，因为日期对象没有此类值。 如果仍然使用它们，则将0替换为它们。

Python strftime（）格式指令 (Python strftime() format directives)

Following table list outs the most commonly used formatting directive that can be used in format string.

下表列出了可以在格式字符串中使用的最常用的格式指令。

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Python strftime（）示例 (Python strftime() example)

日期时间模块 (datetime module)

Let’s look at some examples of using strftime() function with datetime module.

让我们看一些将strftime（）函数与datetime模块一起使用的示例。

import datetimedt = datetime.datetime.now()print('DateTime in Default Formatting:', dt)print('Formatted DateTime', dt.strftime("%m/%d/%y %H:%M:%S"))print("Current year:", dt.strftime("%Y"))
print("Month of year:", dt.strftime("%B"))
print("Week number of the year:", dt.strftime("%W"))
print("Weekday of the week:", dt.strftime("%w"))
print("Day of year:", dt.strftime("%j"))
print("Day of the month:", dt.strftime("%d"))
print("Day of week:", dt.strftime("%A"))

Output:

输出：

DateTime in Default Formatting: 2018-09-17 12:10:48.081992
Formatted DateTime 09/17/18 12:10:48
Current year: 2018
Month of year: September
Week number of the year: 38
Weekday of the week: 1
Day of year: 260
Day of the month: 17
Day of week: Monday

时间模块 (time module)

import time
seconds = time.time()
t = time.localtime(seconds)print('Time struct_time object:', t)
print('Time object with pre-defined formatting:', time.asctime(t))print('Formatted Time:', time.strftime("%m/%d/%y %H:%M:%S", t))print("Current year:", time.strftime("%Y", t))
print("Month of year:", time.strftime("%B", t))
print("Week number of the year:", time.strftime("%W", t))
print("Weekday of the week:", time.strftime("%w", t))
print("Day of year:", time.strftime("%j", t))
print("Day of the month:", time.strftime("%d", t))
print("Day of week:", time.strftime("%A", t))

时区 (TimeZone)

We know that the default datetime object doesn’t have timezone information, let’s see what is the output if we try to print its timezone.

我们知道默认的datetime对象没有时区信息，让我们看看尝试打印其时区的输出是什么。

print("TimeZone:", dt.strftime("%Z"))

Output: TimeZone:

输出：时TimeZone:

Let’s see the output with time module object.

让我们看一下带有时间模块对象的输出。

print("TimeZone:", time.strftime("%Z", t))

Output: TimeZone: IST

输出：时TimeZone: IST

We can use pytz module to create a timezone aware datetime object.

我们可以使用pytz模块创建一个时区感知的datetime对象。

import pytz
utc = pytz.utc
dt = datetime.datetime.now(utc)
print("TimeZone:", dt.strftime("%Z"))

Output: TimeZone: UTC

输出：时TimeZone: UTC

References: datetime strftime(), time strftime()

参考： datetime strftime（） ， 时间strftime（）

翻译自: https://www.journaldev.com/23324/python-strftime