dayofweek | 易学教程

How to get first day of a given week number in Java

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问题 Let me explain myself. By knowing the week number and the year of a date: Date curr = new Date(); Calendar cal = Calendar.getInstance(); cal.setTime(curr); int nweek = cal.WEEK_OF_YEAR; int year = cal.YEAR; But now I don't know how to get the date of the first day of that week. I've been looking in Calendar, Date, DateFormat but nothing that may be useful... Any suggestion? (working in Java) 回答1: Those fields does not return the values. Those are constants which identifies the fields in the

How can I get the 4 Mondays of a month with js?

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问题 I'm building a chart where the x-axis should be the four weeks of a month. I would like to display only the four Mondays of that month. I already have the currentMonth and the currentYear variables, and I know how to get the first day of the month. All I need is to get the four Mondays of a month in an array. And all of this in the same JavaScript file. I'm pretty lost within my programming logic, and I've seen plenty of solutions that don't fit my use case. Right now, I have: var date = new

How to get the integer value of day of week

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问题 How do I get the day of a week in integer format? I know ToString will return only a string. DateTime ClockInfoFromSystem = DateTime.Now; int day1; string day2; day1= ClockInfoFromSystem.DayOfWeek.ToString(); /// it is not working day2= ClockInfoFromSystem.DayOfWeek.ToString(); /// it gives me string 回答1: Use day1 = (int)ClockInfoFromSystem.DayOfWeek; 回答2: int day = (int)DateTime.Now.DayOfWeek; First day of the week: Sunday (with a value of zero) 回答3: If you want to set first day of the week

How to get the day of week and the month of the year?

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I don't know much about Javascript, and the other questions I found are related to operations on dates, not only getting the information as I need it. Objective I wish to get the date as below-formatted: Printed on Thursday, 27 January 2011 at 17:42:21 So far, I got the following: var now = new Date(); var h = now.getHours(); var m = now.getMinutes(); var s = now.getSeconds(); h = checkTime(h); m = checkTime(m); s = checkTime(s); var prnDt = "Printed on Thursday, " + now.getDate() + " January " + now.getFullYear() + " at " + h + ":" + m + ":" s; I now need to know how to get the day of week

Correctness of Sakamoto's algorithm to find the day of week

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问题 I am using Sakamoto\'s algorithm to find out the day of week from a given date. Can anybody tell me the correctness of this algorithm? I just want this from 2000 to 2099. The algorithm from Wikipedia is given for reference. int dow(int y, int m, int d) { static int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4}; y -= m < 3; return (y + y/4 - y/100 + y/400 + t[m-1] + d) % 7; } 回答1: Well, you can tell just by looking at it that it is correct... Assuming that the t[] array is correct, which you can

DateTime.DayOfWeek micro optimization

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问题 First of all: I\'m asking this question just for fun and eager to learn. I have to admit I love to mess around with micro-optimizations (Although they have never led to any significant increase in speed in any of my developments). The DateTime.DayOfWeek method does not represent a bottleneck in any application of mine. And it is highly unlikely to be a problem in any other. If anyone is thinking that this method has an impact on the performance of his application, he should think about When

How to group by week in MySQL?

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问题 Oracle\'s table server offers a built-in function, TRUNC(timestamp,\'DY\') . This function converts any timestamp to midnight on the previous Sunday. What\'s the best way to do this in MySQL? Oracle also offers TRUNC(timestamp,\'MM\') to convert a timestamp to midnight on the first day of the month in which it occurs. In MySQL, this one is straightforward: TIMESTAMP(DATE_FORMAT(timestamp, \'%Y-%m-01\')) But this DATE_FORMAT trick won\'t work for weeks. I\'m aware of the WEEK(timestamp)

How to get the day of week and the month of the year?

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问题 I don\'t know much about Javascript, and the other questions I found are related to operations on dates, not only getting the information as I need it. Objective I wish to get the date as below-formatted: Printed on Thursday, 27 January 2011 at 17:42:21 So far, I got the following: var now = new Date(); var h = now.getHours(); var m = now.getMinutes(); var s = now.getSeconds(); h = checkTime(h); m = checkTime(m); s = checkTime(s); var prnDt = \"Printed on Thursday, \" + now.getDate() + \"