PyQt5学习笔记(01)--date&time

本文翻译及代码来自zetcode.com

PyQt5中有QDate、QDateTime、QTime等类来处理时间和日期。

QDate is a class for working with a calender date in Gregorian calendar.

It has methods for determining the date, comparing, or manipulating dates.

QTime class works with a clock time.

It provides methods for comparing time, determining the time and various other time manipulating methods.

QDateTime is a class that combines both QDate and QTime objects into one object.

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Current date and time

PyQt5 中 currentdDate(), currentTime()和currentDateTime()方法来表示当前日期和时间。

from PyQt5.QtCore import QDate, QTime, QDateTime, Qt

now = QDate.currentDate()   # returns the current date
print(now.toString(Qt.ISODate))
print(now.toString(Qt.DefaultLocaleLongDate))


datetime = QDateTime.currentDateTime()  # returns the current date and time
print(datetime.toString())


time = QTime.currentTime()  # returns the current time
print(time.toString(Qt.DefaultLocaleLongDate))

其中：

print(now.toString(Qt.ISODate))
print(now.toString(Qt.DefaultLocaleLongDate))

Qt.ISODate和Qt.DefaultLocalLongDate将值传递给toString()方法，打印出两种不同格式的日期
下面为上述代码的输出：

2018-06-29
2018年6月29日星期五
周五 6月 29 21:03:54 2018
CST 下午9:03:54

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UTC time

协调世界时，又称世界统一时间、世界标准时间、国际协调时间，简称UTC。
网络时间协议就是协调世界时在互联网中使用的一种方式

from PyQt5.QtCore import QDateTime, Qt

now = QDateTime.currentDateTime()

print("Local datetime:: ", now.toString(Qt.ISODate))
print("Universal datetime: ", now.toUTC().toString(Qt.ISODate))

print("The offset from UTC is : {0} seconds".format(now.offsetFromUtc()))

currentDatetime()方法返回当前本地的日期和时间

toLocalTime()方法可以将世界时间转换为本地时间

toUTC()方法得到世界时间

offsetFromUtc()给出本地时间和世界时间的差值

以下是上述代码的输出：

Local datetime::  2018-06-29T23:01:38
Universal datetime:  2018-06-29T15:01:38Z
The offset from UTC is : 28800 seconds

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Number of days

daysInMonth()方法返回日期所在月份的天数
daysInYear()方法返回日期所在年份的天数
dayOfWeek()方法返回日期所在月份的第几周
dayOfYear()方法返回日期所在的年份的第几天

from PyQt5.QtCore import QDate, Qt

now = QDate.currentDate()

d = QDate(2018, 1, 17)

print("Days in month: {0}".format(d.daysInMonth()))
print("Day of week: {0}".format(d.dayOfWeek()))
print("Days in year: {0}".format(d.daysInYear()))
print("Day of year: {0}".format(d.dayOfYear()))

以下是输出结果：

Days in month: 31
Day of week: 3
Days in year: 365
Day of year: 17

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Difference in days

daysTo()方法返回两个日期的差值

from PyQt5.QtCore import QDate

mDay1 = QDate(2018, 1, 17)
mDay2 = QDate(2018, 6, 30)

now = QDate.currentDate()

dayspassed =mDay1.daysTo(now)

print("{0} days have passed since last Memorial Day".format(dayspassed))

nofdays = now.daysTo(mDay2)

print("There are {0} day until next Memorial Day".format(nofdays))

以下是代码的输出：

163 days have passed since last Memorial Day
There are 1 day until next Memorial Day

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Datetime arithmetic

日期算术

from PyQt5.QtCore import QDateTime, Qt

now = QDateTime.currentDateTime()

print("Today:", now.toString(Qt.ISODate))
print("Adding 12 days: {0}".format(now.addDays(12).toString(Qt.ISODate)))
print("Subtracting 22 days: {0}".format(now.addDays(-22).toString(Qt.ISODate)))

print("Adding 50 seconds: {0}".format(now.addSecs(50).toString(Qt.ISODate)))
print("Adding 3 months: {0}".format(now.addMonths(3).toString(Qt.ISODate)))
print("Adding 12 years: {0}".format(now.addYears(12).toString(Qt.ISODate)))

以下是输出：

Today: 2018-06-30T00:10:31
Adding 12 days: 2018-07-12T00:10:31
Subtracting 22 days: 2018-06-08T00:10:31
Adding 50 seconds: 2018-06-30T00:11:21
Adding 3 months: 2018-09-30T00:10:31
Adding 12 years: 2030-06-30T00:10:31

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