leap-year

Someone on JSPerf dropped an amazingly fast implementation for checking leap years of the ISO calendar (link: Odd bit manipulations ): function isLeapYear(year) { return !(year & 3 || year & 15 && !(year % 25)); } Using Node.js, I quickly checked it against two other one-liner implementations I know. function isLeapClassic(y) { return (y % 4 == 0) && !(y % 100 == 0) || (y % 400 == 0); } function isLeapXOR(y) { return (y % 4 == 0) ^ (y % 100 == 0) ^ (y % 400 == 0); } function isLeapBitwise(y) { return !(y & 3 || y & 15 && !(y % 25)); } //quick'n'dirty test on a small range! //works with

I have a HTML page with 3 dropdowns for the month, day and year and I was wondering if there was a way to populate the month drop down properly depending on the month and year. I haven't done this before on the client side, but it looks like a lot of controls like the jQuery DatePicker are doing that behind the scenes. You can play with date objects: var monthStart = new Date(year, month, 1); var monthEnd = new Date(year, month + 1, 1); var monthLength = (monthEnd - monthStart) / (1000 * 60 * 60 * 24) Arithmetic with Date objects gives a number of milliseconds. This will even work for December

We need help for regular expression that work with asp.net asp:RegularExpressionValidator to validate date in MMddyy format. Problem we are facing is leap year. Issue is that is it possible to verify through regular expression that it only accepts valid leap year dates like 02/29/2008 is a valid date but 02/29/2010 is not a valid date. Any regular expression that works with "asp:RegularExpressionValidator"? OK, you asked for a regex. Here it is. I think it's immediately obvious why it's not a good idea to validate a date with a regular expression: First, the verbose, commented version to at

How can I get the code below to work when I have a month of february? Currently it is getting to the day and then stopping before getting to the if to determine whether it is a leap year. if (month == 2) { if (day == 29) { if (year % 4 != 0 || year % 100 == 0 && year % 400 != 0) { field.focus(); field.value = month +'/' + ''; } } else if (day > 28) { field.focus(); field.value = month +'/' + ''; } } It's safer to use Date objects for datetime stuff, e.g. isLeap = new Date(year, 1, 29).getMonth() == 1 Since people keep asking about how exactly this works, it has to do with how JS calculates the

I made a program using C to find whether the entered year is a leap year or not. But unfortunately its not working well. It says a year is leap and the preceding year is not leap. #include<stdio.h> #include<conio.h> int yearr(int year); void main(void) { int year; printf("Enter a year:"); scanf("%d",&year); if(!yearr(year)) { printf("It is a leap year."); } else { printf("It is not a leap year"); } getch(); } int yearr(int year) { if((year%4==0)&&(year/4!=0)) return 1; else return 0; } After reading the comments i edited my coding as: #include<stdio.h> #include<conio.h> int yearr(int year);