Iterate through hours in a day

Question

having a DateTime variable, for example:

DateTime testDate = new DateTime(2011,12,15,00,00,00);

how can I implement a foreach loop for every hour of this day?

Something like:

foreach (int myHour in testDate.Date)
{

}

but in this way does not compile.

Answer 1

It is not a good idea to loop 24, because this will not work on days with 25 or 23 hours (time change, daylight saving...).

Use the AddHour function and a target date.

DateTime testDate = new DateTime(2011, 12, 15, 00, 00, 00, DateTimeKind.Local);
DateTime endDate = testDate.AddDays(1);

while (testDate.Date != endDate.Date)
{
    Console.WriteLine(testDate.ToString());
    testDate = testDate.AddHours(1);
}

More Information

• MSDN - DateTimeKind Enumeration

Answer 2

Use for instead:

DateTime date = new DateTime(2011,12,15);
for(int i = 0; i < 24; i++)
{
    DateTime time = date.AddHours(i);
    ...
}

If you really want to use foreach, you could create an extension method like this:

static class DateTimeExtensions
{
    public static IEnumerable<DateTime> GetHours(this DateTime date)
    {
        date = date.Date; // truncate hours
        for(int i = 0; i < 24; i++)
        {
            yield return date.AddHours(i);
        }
    }
}

...

DateTime date = new DateTime(2011,12,15);
foreach (DateTime time in date.GetHours())
{
    ...
}

Answer 3

For those who don't like plain old for loops :) :

DateTime testDate = new DateTime(2011,12,15,00,00,00);
foreach (int hour in Enumerable.Range(0,24)) {
    DateTime dateWithHour = testDate.AddHours(hour);
}

Answer 4

foreach loop works in list but here testDate.Date never gives you hour. so in substitution of it use for loop or do while or while loop.