time — Time access and conversions时间访问和转换

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This module provides various time-related functions. 该模块提供各种与时间相关的功能。For related functionality, see also the datetime and calendar modules.有关相关功能，请参阅datetime和calendar模块。

Although this module is always available, not all functions are available on all platforms. 尽管此模块始终可用，但并非所有功能都在所有平台上可用。Most of the functions defined in this module call platform C library functions with the same name. 本模块中定义的大多数函数都使用相同的名称调用平台C库函数。It may sometimes be helpful to consult the platform documentation, because the semantics of these functions varies among platforms.有时，查阅平台文档可能会有所帮助，因为这些功能的语义因平台而异。

An explanation of some terminology and conventions is in order.一些术语和惯例的解释是有序的。

• The epoch is the point where the time starts, and is platform dependent. 纪元是时间开始的点，取决于平台。For Unix, the epoch is January 1, 1970, 00:00:00 (UTC). 对于Unix，纪元是1970年1月1日00:00:00(UTC)。To find out what the epoch is on a given platform, look at time.gmtime(0).要了解给定平台上的历元是什么，请查看time.gmtime(0)。

• The term seconds since the epoch refers to the total number of elapsed seconds since the epoch, typically excluding leap seconds. 术语“自历元以来的秒数”指自历元以来经过的秒总数，通常不包括闰秒。Leap seconds are excluded from this total on all POSIX-compliant platforms.在所有兼容POSIX的平台上，闰秒不包括在总数中。

• The functions in this module may not handle dates and times before the epoch or far in the future. 此模块中的函数可能无法处理纪元之前或遥远未来的日期和时间。The cut-off point in the future is determined by the C library; for 32-bit systems, it is typically in 2038.未来的分界点由C库决定；对于32位系统，通常在2038年。

• Function strptime() can parse 2-digit years when given %y format code. 当给定%y格式代码时，函数strptime()可以解析两位数的年份。When 2-digit years are parsed, they are converted according to the POSIX and ISO C standards: values 69–99 are mapped to 1969–1999, and values 0–68 are mapped to 2000–2068.解析两位数年份时，将根据POSIX和ISO C标准进行转换：69-99的值映射到1969-1999，0-68的值映射到2000-2068。

• UTC is Coordinated Universal Time (formerly known as Greenwich Mean Time, or GMT). UTC是协调世界时（以前称为格林威治标准时间或GMT）。The acronym UTC is not a mistake but a compromise between English and French.缩写UTC不是一个错误，而是英语和法语之间的折衷。

• DST is Daylight Saving Time, an adjustment of the timezone by (usually) one hour during part of the year. 夏令时是夏令时，在一年中的部分时间内（通常）将时区调整一小时。DST rules are magic (determined by local law) and can change from year to year. DST规则很神奇（由当地法律决定），每年都可能发生变化。The C library has a table containing the local rules (often it is read from a system file for flexibility) and is the only source of True Wisdom in this respect.C库有一个包含局部规则的表（为了灵活性，通常从系统文件中读取），它是这方面真正智慧的唯一来源。

• The precision of the various real-time functions may be less than suggested by the units in which their value or argument is expressed. 各种实时函数的精度可能低于表示其值或参数的单位所建议的精度。E.g. on most Unix systems, the clock “ticks” only 50 or 100 times a second.在大多数Unix系统上，时钟每秒只“滴答”50或100次。

• On the other hand, the precision of time() and sleep() is better than their Unix equivalents: times are expressed as floating point numbers, time() returns the most accurate time available (using Unix gettimeofday() where available), and sleep() will accept a time with a nonzero fraction (Unix select() is used to implement this, where available).另一方面，time()和sleep()的精度优于其Unix等价物：时间用浮点数表示，time()返回可用的最准确时间（在可用的情况下使用Unix gettimeofday()），sleep()将接受非零分数的时间（在可用的情况下，使用Unix select()实现）。

• The time value as returned by gmtime(), localtime(), and strptime(), and accepted by asctime(), mktime() and strftime(), is a sequence of 9 integers. 由gmtime()、localtime()和strptime()返回并由asctime()、mktime()和strftime()接受的时间值是9个整数的序列。The return values of gmtime(), localtime(), and strptime() also offer attribute names for individual fields.gmtime()、localtime()和strptime()的返回值还为各个字段提供了属性名称。

  See struct_time for a description of these objects.有关这些对象的描述，请参阅struct_time。

  Changed in version 3.3:版本3.3中更改： The struct_time type was extended to provide the tm_gmtoff and tm_zone attributes when platform supports corresponding struct tm members.当平台支持相应的struct tm成员时，struct_time类型被扩展以提供tm_gmtoff和tm_zone属性。

  Changed in version 3.6:版本3.6中更改： The struct_time attributes tm_gmtoff and tm_zone are now available on all platforms.struct_time属性tm_gmtoff和tm_zone现在在所有平台上都可用。

• Use the following functions to convert between time representations:使用以下函数在时间表示之间进行转换：

  From	To	Use
  seconds since the epoch从新纪元开始的秒数	struct_time in UTC用UTC表示	gmtime()
  seconds since the epoch从新纪元开始的秒数	struct_time in local time本地时间的struct_time	localtime()
  struct_time in UTC用UTC表示	seconds since the epoch从新纪元开始的秒数	calendar.timegm()
  struct_time in local time本地时间的struct_time	seconds since the epoch从新纪元开始的秒数	mktime()

Functions函数

time.asctime([t])

Convert a tuple or struct_time representing a time as returned by gmtime() or localtime() to a string of the following form: 'Sun Jun 20 23:21:05 1993'. The day field is two characters long and is space padded if the day is a single digit, e.g.: 'Wed Jun 9 04:26:40 1993'.日期字段有两个字符长，如果日期是一个数字，则用空格填充，例如：'Wed Jun 9 04:26:40 1993'。

If t is not provided, the current time as returned by localtime() is used. 如果未提供t，则使用localtime()返回的当前时间。Locale information is not used by asctime().asctime()未使用区域设置信息。

Note

Unlike the C function of the same name, asctime() does not add a trailing newline.与同名的C函数不同，asctime()不添加尾随换行符。

time.pthread_getcpuclockid(thread_id)

Return the clk_id of the thread-specific CPU-time clock for the specified thread_id.返回指定thread_id的特定于线程的CPU时钟的clk_id。

Use threading.get_ident() or the ident attribute of threading.Thread objects to get a suitable value for thread_id.

Warning

Passing an invalid or expired thread_id may result in undefined behavior, such as segmentation fault.传递无效或过期的thread_id可能会导致未定义的行为，例如分段错误。

Availability: Unix (see the man page for pthread_getcpuclockid(3) for further information).

New in version 3.7.版本3.7中新增。

time.clock_getres(clk_id)

Return the resolution (precision) of the specified clock clk_id. 返回指定时钟clk_id的分辨率（精度）。Refer to Clock ID Constants for a list of accepted values for clk_id.

Availability: Unix.

New in version 3.3.版本3.3中新增。

time.clock_gettime(clk_id) → float

Return the time of the specified clock clk_id. Refer to Clock ID Constants for a list of accepted values for clk_id.

Use clock_gettime_ns() to avoid the precision loss caused by the float type.

Availability: Unix.

New in version 3.3.版本3.3中新增。

time.clock_gettime_ns(clk_id) → int

Similar to clock_gettime() but return time as nanoseconds.类似于clock_gettime()，但返回时间为纳秒。

Availability: Unix.

New in version 3.7.版本3.7中新增。

time.clock_settime(clk_id, time: float)

Set the time of the specified clock clk_id. Currently, CLOCK_REALTIME is the only accepted value for clk_id.

Use clock_settime_ns() to avoid the precision loss caused by the float type.

Availability: Unix.

New in version 3.3.版本3.3中新增。

time.clock_settime_ns(clk_id, time: int)

Similar to clock_settime() but set time with nanoseconds.类似于clock_settime()，但以纳秒设置时间。

Availability: Unix.

New in version 3.7.版本3.7中新增。

time.ctime([secs])

Convert a time expressed in seconds since the epoch to a string of a form: 'Sun Jun 20 23:21:05 1993' representing local time. The day field is two characters long and is space padded if the day is a single digit, e.g.: 'Wed Jun 9 04:26:40 1993'.

If secs is not provided or None, the current time as returned by time() is used. ctime(secs) is equivalent to asctime(localtime(secs)). Locale information is not used by ctime().

time.get_clock_info(name)

Get information on the specified clock as a namespace object. 作为命名空间对象获取指定时钟的信息。Supported clock names and the corresponding functions to read their value are:支持的时钟名称和读取其值的相应函数为：

• 'monotonic': time.monotonic()

• 'perf_counter': time.perf_counter()

• 'process_time': time.process_time()

• 'thread_time': time.thread_time()

• 'time': time.time()

The result has the following attributes:结果具有以下属性：

• adjustable: True if the clock can be changed automatically (e.g. by a NTP daemon) or manually by the system administrator, False otherwise

• implementation: The name of the underlying C function used to get the clock value. Refer to Clock ID Constants for possible values.

• monotonic: True if the clock cannot go backward, False otherwise

• resolution: The resolution of the clock in seconds (float)

New in version 3.3.版本3.3中新增。

time.gmtime([secs])

Convert a time expressed in seconds since the epoch to a struct_time in UTC in which the dst flag is always zero. If secs is not provided or None, the current time as returned by time() is used. Fractions of a second are ignored. See above for a description of the struct_time object. See calendar.timegm() for the inverse of this function.

time.localtime([secs])

Like gmtime() but converts to local time. If secs is not provided or None, the current time as returned by time() is used. The dst flag is set to 1 when DST applies to the given time.

localtime() may raise OverflowError, if the timestamp is outside the range of values supported by the platform C localtime() or gmtime() functions, and OSError on localtime() or gmtime() failure. It’s common for this to be restricted to years between 1970 and 2038.

time.mktime(t)

This is the inverse function of localtime(). Its argument is the struct_time or full 9-tuple (since the dst flag is needed; use -1 as the dst flag if it is unknown) which expresses the time in local time, not UTC. It returns a floating point number, for compatibility with time(). If the input value cannot be represented as a valid time, either OverflowError or ValueError will be raised (which depends on whether the invalid value is caught by Python or the underlying C libraries). The earliest date for which it can generate a time is platform-dependent.

time.monotonic() → float

Return the value (in fractional seconds) of a monotonic clock, i.e. a clock that cannot go backwards. The clock is not affected by system clock updates. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.

Use monotonic_ns() to avoid the precision loss caused by the float type.

New in version 3.3.版本3.3中新增。

Changed in version 3.5:版本3.5中更改： The function is now always available and always system-wide.该功能现在始终可用，并且在系统范围内始终可用。

Changed in version 3.10:版本3.10中更改： On macOS, the function is now system-wide.在macOS上，该功能现在是全系统的。

time.monotonic_ns() → int

Similar to monotonic(), but return time as nanoseconds.

New in version 3.7.版本3.7中新增。

time.perf_counter() → float

Return the value (in fractional seconds) of a performance counter, i.e. a clock with the highest available resolution to measure a short duration. It does include time elapsed during sleep and is system-wide. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.

Use perf_counter_ns() to avoid the precision loss caused by the float type.

New in version 3.3.版本3.3中新增。

Changed in version 3.10:版本3.10中更改： On Windows, the function is now system-wide.在Windows上，该功能现在是全系统的。

time.perf_counter_ns() → int

Similar to perf_counter(), but return time as nanoseconds.

New in version 3.7.版本3.7中新增。

time.process_time() → float

Return the value (in fractional seconds) of the sum of the system and user CPU time of the current process. 返回当前进程的系统和用户CPU时间之和的值（以分数秒为单位）。It does not include time elapsed during sleep. 它不包括睡眠期间经过的时间。It is process-wide by definition. 从定义上讲，它是全过程的。The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.返回值的参考点未定义，因此只有两个调用结果之间的差异有效。

Use process_time_ns() to avoid the precision loss caused by the float type.

New in version 3.3.版本3.3中新增。

time.process_time_ns() → int

Similar to process_time() but return time as nanoseconds.类似于process_time()，但返回时间为纳秒。

New in version 3.7.版本3.7中新增。

time.sleep(secs)

Suspend execution of the calling thread for the given number of seconds. 在给定的秒数内暂停调用线程的执行。The argument may be a floating point number to indicate a more precise sleep time. 参数可以是浮点数，以指示更精确的睡眠时间。The actual suspension time may be less than that requested because any caught signal will terminate the sleep() following execution of that signal’s catching routine. 实际暂停时间可能小于请求的暂停时间，因为任何捕获的信号都将在执行该信号的捕获例程后终止sleep()。Also, the suspension time may be longer than requested by an arbitrary amount because of the scheduling of other activity in the system.此外，由于系统中其他活动的调度，暂停时间可能比请求的时间长任意数量。

Changed in version 3.5:版本3.5中更改： The function now sleeps at least secs even if the sleep is interrupted by a signal, except if the signal handler raises an exception (see PEP 475 for the rationale).

time.strftime(format[, t])

Convert a tuple or struct_time representing a time as returned by gmtime() or localtime() to a string as specified by the format argument. If t is not provided, the current time as returned by localtime() is used. format must be a string. ValueError is raised if any field in t is outside of the allowed range.

0 is a legal argument for any position in the time tuple; if it is normally illegal the value is forced to a correct one.0是时间元组中任何位置的合法参数；如果该值通常是非法的，则强制将其设置为正确的值。

The following directives can be embedded in the format string. 以下指令可以嵌入format字符串中。They are shown without the optional field width and precision specification, and are replaced by the indicated characters in the strftime() result:它们在显示时没有可选的字段宽度和精度规范，并被strftime()结果中的指示字符替换：

Directive指令	Meaning意思	Notes笔记
%a	Locale’s abbreviated weekday name.区域设置的缩写工作日名称。
%A	Locale’s full weekday name.区域设置的完整工作日名称。
%b	Locale’s abbreviated month name.区域设置的缩写月份名称。
%B	Locale’s full month name.区域设置的完整月份名称。
%c	Locale’s appropriate date and time representation.区域设置的适当日期和时间表示。
%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].以十进制数字表示的年份日期[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]. 一年中的周数（星期日为一周的第一天），以十进制数字[00,53]表示。All days in a new year preceding the first Sunday are considered to be in week 0.新年中第一个星期日之前的所有日子都被视为在第0周。	(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]. 一年中的周数（星期一为一周的第一天），以十进制数字[00,53]表示。All days in a new year preceding the first Monday are considered to be in week 0.新年第一个星期一之前的所有日子都被视为在第0周。	(3)
%x	Locale’s appropriate date representation.区域设置的适当日期表示。
%X	Locale’s appropriate time representation.区域设置的适当时间表示。
%y	Year without century as a decimal number [00,99].以十进制数字[00,99]表示的无世纪年份。
%Y	Year with century as a decimal number.以世纪为小数的年份。
%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]. 时区偏移量，表示与UTC/GMT的正时差或负时差，形式为+HHMM或-HHMM，其中H表示十进制小时数，M表示十进制分钟数[-23:59, +23:59]。1
%Z	Time zone name (no characters if no time zone exists). 时区名称（如果不存在时区，则不包含字符）。Deprecated. 已弃用。1
%%	A literal '%' character.文字字符'%'。

Notes:

1. When used with the strptime() function, the %p directive only affects the output hour field if the %I directive is used to parse the hour.

2. The range really is 0 to 61; value 60 is valid in timestamps representing leap seconds and value 61 is supported for historical reasons.

3. When used with the strptime() function, %U and %W are only used in calculations when the day of the week and the year are specified.

Here is an example, a format for dates compatible with that specified in the RFC 2822 Internet email standard. 以下是一个示例，与RFC 2822互联网电子邮件标准中指定的日期兼容的格式。1

>>> from time import gmtime, strftime
>>> strftime("%a, %d %b %Y %H:%M:%S +0000", gmtime())
'Thu, 28 Jun 2001 14:17:15 +0000'

Additional directives may be supported on certain platforms, but only the ones listed here have a meaning standardized by ANSI C. 某些平台上可能支持其他指令，但只有此处列出的指令具有ANSI C标准化的含义。To see the full set of format codes supported on your platform, consult the strftime(3) documentation.要查看您的平台上支持的全套格式代码，请参阅strftime(3)文档。

On some platforms, an optional field width and precision specification can immediately follow the initial '%' of a directive in the following order; this is also not portable. 在某些平台上，可选的字段宽度和精度规范可以按照以下顺序紧跟指令的初始'%'；这也是不可移植的。The field width is normally 2 except for %j where it is 3.字段宽度通常为2，但%j除外，其中为3。

time.strptime(string[, format])

Parse a string representing a time according to a format. 根据格式解析表示时间的字符串。The return value is a struct_time as returned by gmtime() or localtime().

The format parameter uses the same directives as those used by strftime(); it defaults to "%a %b %d %H:%M:%S %Y" which matches the formatting returned by ctime(). If string cannot be parsed according to format, or if it has excess data after parsing, ValueError is raised. The default values used to fill in any missing data when more accurate values cannot be inferred are (1900, 1, 1, 0, 0, 0, 0, 1, -1). Both string and format must be strings.

For example:

>>> import time
>>> time.strptime("30 Nov 00", "%d %b %y")
time.struct_time(tm_year=2000, tm_mon=11, tm_mday=30, tm_hour=0, tm_min=0,
                 tm_sec=0, tm_wday=3, tm_yday=335, tm_isdst=-1)

Support for the %Z directive is based on the values contained in tzname and whether daylight is true. Because of this, it is platform-specific except for recognizing UTC and GMT which are always known (and are considered to be non-daylight savings timezones).

Only the directives specified in the documentation are supported. Because strftime() is implemented per platform it can sometimes offer more directives than those listed. But strptime() is independent of any platform and thus does not necessarily support all directives available that are not documented as supported.

classtime.struct_time

The type of the time value sequence returned by gmtime(), localtime(), and strptime(). It is an object with a named tuple interface: values can be accessed by index and by attribute name. The following values are present:

Index	Attribute	Values
0	tm_year	(for example, 1993)
1	tm_mon	range [1, 12]
2	tm_mday	range [1, 31]
3	tm_hour	range [0, 23]
4	tm_min	range [0, 59]
5	tm_sec	range [0, 61]; see (2) in strftime() description
6	tm_wday	range [0, 6], Monday is 0
7	tm_yday	range [1, 366]
8	tm_isdst	0, 1 or -1; see below
N/A	tm_zone	abbreviation of timezone name时区名称的缩写
N/A	tm_gmtoff	offset east of UTC in secondsUTC以东偏移（秒）

Note that unlike the C structure, the month value is a range of [1, 12], not [0, 11].

In calls to mktime(), tm_isdst may be set to 1 when daylight savings time is in effect, and 0 when it is not. A value of -1 indicates that this is not known, and will usually result in the correct state being filled in.

When a tuple with an incorrect length is passed to a function expecting a struct_time, or having elements of the wrong type, a TypeError is raised.

time.time() → float

Return the time in seconds since the epoch as a floating point number. The specific date of the epoch and the handling of leap seconds is platform dependent. On Windows and most Unix systems, the epoch is January 1, 1970, 00:00:00 (UTC) and leap seconds are not counted towards the time in seconds since the epoch. This is commonly referred to as Unix time. To find out what the epoch is on a given platform, look at gmtime(0).

Note that even though the time is always returned as a floating point number, not all systems provide time with a better precision than 1 second. While this function normally returns non-decreasing values, it can return a lower value than a previous call if the system clock has been set back between the two calls.

The number returned by time() may be converted into a more common time format (i.e. year, month, day, hour, etc…) in UTC by passing it to gmtime() function or in local time by passing it to the localtime() function. In both cases a struct_time object is returned, from which the components of the calendar date may be accessed as attributes.

Use time_ns() to avoid the precision loss caused by the float type.

time.time_ns() → int

Similar to time() but returns time as an integer number of nanoseconds since the epoch.

New in version 3.7.版本3.7中新增。

time.thread_time() → float

Return the value (in fractional seconds) of the sum of the system and user CPU time of the current thread. 返回当前线程的系统和用户CPU时间之和的值（以小数秒为单位）。It does not include time elapsed during sleep. 它不包括睡眠期间经过的时间。It is thread-specific by definition. 根据定义，它是特定于线程的。The reference point of the returned value is undefined, so that only the difference between the results of two calls in the same thread is valid.返回值的参考点未定义，因此只有同一线程中两个调用的结果之间的差异才有效。

Use thread_time_ns() to avoid the precision loss caused by the float type.

Availability: Windows, Linux, Unix systems supporting CLOCK_THREAD_CPUTIME_ID.

New in version 3.7.版本3.7中新增。

time.thread_time_ns() → int

Similar to thread_time() but return time as nanoseconds.类似于thread_time()，但返回时间为纳秒。

New in version 3.7.版本3.7中新增。

time.tzset()

Reset the time conversion rules used by the library routines. 重置库例程使用的时间转换规则。The environment variable TZ specifies how this is done. It will also set the variables tzname (from the TZ environment variable), timezone (non-DST seconds West of UTC), altzone (DST seconds west of UTC) and daylight (to 0 if this timezone does not have any daylight saving time rules, or to nonzero if there is a time, past, present or future when daylight saving time applies).

Availability: Unix.

Note

Although in many cases, changing the TZ environment variable may affect the output of functions like localtime() without calling tzset(), this behavior should not be relied on.

The TZ environment variable should contain no whitespace.

The standard format of the TZ environment variable is (whitespace added for clarity):

std offset [dst [offset [,start[/time], end[/time]]]]

Where the components are:

std and dst

Three or more alphanumerics giving the timezone abbreviations. 给出时区缩写的三个或更多字母数字。These will be propagated into time.tzname

offset

The offset has the form: ± hh[:mm[:ss]]. This indicates the value added the local time to arrive at UTC. 这表示到达UTC的当地时间的附加值。If preceded by a ‘-’, the timezone is east of the Prime Meridian; otherwise, it is west. If no offset follows dst, summer time is assumed to be one hour ahead of standard time.

start[/time], end[/time]

Indicates when to change to and back from DST. 指示何时更改DST和从DST返回。The format of the start and end dates are one of the following:开始和结束日期的格式如下：

Jn

The Julian day n (1 <= n <= 365). Leap days are not counted, so in all years February 28 is day 59 and March 1 is day 60.

n

The zero-based Julian day (0 <= n <= 365). Leap days are counted, and it is possible to refer to February 29.

Mm.n.d

The d’th day (0 <= d <= 6) of week n of month m of the year (1 <= n <= 5, 1 <= m <= 12, where week 5 means “the last d day in month m” which may occur in either the fourth or the fifth week). Week 1 is the first week in which the d’th day occurs. Day zero is a Sunday.

time has the same format as offset except that no leading sign (‘-’ or ‘+’) is allowed. The default, if time is not given, is 02:00:00.

>>> os.environ['TZ'] = 'EST+05EDT,M4.1.0,M10.5.0'
>>> time.tzset()
>>> time.strftime('%X %x %Z')
'02:07:36 05/08/03 EDT'
>>> os.environ['TZ'] = 'AEST-10AEDT-11,M10.5.0,M3.5.0'
>>> time.tzset()
>>> time.strftime('%X %x %Z')
'16:08:12 05/08/03 AEST'

On many Unix systems (including *BSD, Linux, Solaris, and Darwin), it is more convenient to use the system’s zoneinfo (tzfile(5)) database to specify the timezone rules. To do this, set the TZ environment variable to the path of the required timezone datafile, relative to the root of the systems ‘zoneinfo’ timezone database, usually located at /usr/share/zoneinfo. For example, 'US/Eastern', 'Australia/Melbourne', 'Egypt' or 'Europe/Amsterdam'.

>>> os.environ['TZ'] = 'US/Eastern'
>>> time.tzset()
>>> time.tzname
('EST', 'EDT')
>>> os.environ['TZ'] = 'Egypt'
>>> time.tzset()
>>> time.tzname
('EET', 'EEST')

Clock ID Constants

These constants are used as parameters for clock_getres() and clock_gettime().这些常数用作clock_getres()和clock_gettime()的参数。

time.CLOCK_BOOTTIME

Identical to CLOCK_MONOTONIC, except it also includes any time that the system is suspended.与CLOCK_MONOTONIC相同，只是它还包括系统暂停的任何时间。

This allows applications to get a suspend-aware monotonic clock without having to deal with the complications of CLOCK_REALTIME, which may have discontinuities if the time is changed using settimeofday() or similar.

Availability: Linux 2.6.39 or later.

New in version 3.7.版本3.7中新增。

time.CLOCK_HIGHRES

The Solaris OS has a CLOCK_HIGHRES timer that attempts to use an optimal hardware source, and may give close to nanosecond resolution. CLOCK_HIGHRES is the nonadjustable, high-resolution clock.

Availability: Solaris.

New in version 3.3.版本3.3中新增。

time.CLOCK_MONOTONIC

Clock that cannot be set and represents monotonic time since some unspecified starting point.无法设置的时钟，表示自某个未指定的起点以来的单调时间。

Availability: Unix.

New in version 3.3.版本3.3中新增。

time.CLOCK_MONOTONIC_RAW

Similar to CLOCK_MONOTONIC, but provides access to a raw hardware-based time that is not subject to NTP adjustments.

Availability: Linux 2.6.28 and newer, macOS 10.12 and newer.

New in version 3.3.版本3.3中新增。

time.CLOCK_PROCESS_CPUTIME_ID

High-resolution per-process timer from the CPU.

Availability: Unix.

New in version 3.3.版本3.3中新增。

time.CLOCK_PROF

High-resolution per-process timer from the CPU.

Availability: FreeBSD, NetBSD 7 or later, OpenBSD.

New in version 3.7.版本3.7中新增。

time.CLOCK_TAI

International Atomic Time

The system must have a current leap second table in order for this to give the correct answer. 系统必须具有当前的闰秒表才能给出正确答案。PTP or NTP software can maintain a leap second table.PTP或NTP软件可以维护闰秒表。

Availability: Linux.

New in version 3.9.版本3.9中新增。

time.CLOCK_THREAD_CPUTIME_ID

Thread-specific CPU-time clock.

Availability: Unix.

New in version 3.3.版本3.3中新增。

time.CLOCK_UPTIME

Time whose absolute value is the time the system has been running and not suspended, providing accurate uptime measurement, both absolute and interval.时间，其绝对值是系统已运行且未暂停的时间，提供准确的正常运行时间测量，包括绝对时间和间隔时间。

Availability: FreeBSD, OpenBSD 5.5 or later.

New in version 3.7.版本3.7中新增。

time.CLOCK_UPTIME_RAW

Clock that increments monotonically, tracking the time since an arbitrary point, unaffected by frequency or time adjustments and not incremented while the system is asleep.单调递增的时钟，跟踪从任意点开始的时间，不受频率或时间调整的影响，并且在系统睡眠时不递增。

Availability: macOS 10.12 and newer.

New in version 3.8.版本3.8中新增。

The following constant is the only parameter that can be sent to clock_settime().以下常数是唯一可以发送到clock_settime()的参数。

time.CLOCK_REALTIME

System-wide real-time clock. Setting this clock requires appropriate privileges.全系统实时时钟。设置此时钟需要适当的权限。

Availability: Unix.

New in version 3.3.版本3.3中新增。

Timezone Constants

time.altzone

The offset of the local DST timezone, in seconds west of UTC, if one is defined. 本地DST时区的偏移量，以UTC以西的秒为单位（如果已定义）。This is negative if the local DST timezone is east of UTC (as in Western Europe, including the UK). 如果当地夏令时时区位于UTC以东（如西欧，包括英国），则为负值。Only use this if daylight is nonzero. 仅当daylight不为零时使用此选项。See note below.请参阅以下注释。

time.daylight

Nonzero if a DST timezone is defined. 如果定义了DST时区，则为非零。See note below.请参阅以下注释。

time.timezone

The offset of the local (non-DST) timezone, in seconds west of UTC (negative in most of Western Europe, positive in the US, zero in the UK). 本地（非夏令时）时区的偏移量，以UTC以西的秒为单位（西欧大部分地区为负，美国为正，英国为零）。See note below.请参阅以下注释。

time.tzname

A tuple of two strings: the first is the name of the local non-DST timezone, the second is the name of the local DST timezone. 由两个字符串组成的元组：第一个是本地非DST时区的名称，第二个是本地DST时区的名称。If no DST timezone is defined, the second string should not be used. 如果未定义DST时区，则不应使用第二个字符串。See note below.请参阅以下注释。

Note

For the above Timezone constants (altzone, daylight, timezone, and tzname), the value is determined by the timezone rules in effect at module load time or the last time tzset() is called and may be incorrect for times in the past. It is recommended to use the tm_gmtoff and tm_zone results from localtime() to obtain timezone information.

See also

Module datetime

More object-oriented interface to dates and times.

Module locale

Internationalization services. 国际化服务。The locale setting affects the interpretation of many format specifiers in strftime() and strptime().区域设置影响strftime()和strptime()中许多格式说明符的解释。

Module calendar

General calendar-related functions. 通用日历相关功能。timegm() is the inverse of gmtime() from this module.

Footnotes

1(1,2,3)

The use of %Z is now deprecated, but the %z escape that expands to the preferred hour/minute offset is not supported by all ANSI C libraries. Also, a strict reading of the original 1982 RFC 822 standard calls for a two-digit year (%y rather than %Y), but practice moved to 4-digit years long before the year 2000. After that, RFC 822 became obsolete and the 4-digit year has been first recommended by RFC 1123 and then mandated by RFC 2822.