DateTime Format Day of Year

Question

Is there a format value for DateTime.ToString("") that will specify the day of the year in three digits?

For example:

• Jan 1, 2012 would be 001
• Feb 1, 2012 would be 032
• Dec 31, 2012 would be 366 (leap year)
• Dec 31, 2011 would be 365

Answer 1

No, you can use DateTime.DayOfYear.ToString("000");

Your examples:

new DateTime(2012, 1, 1).DayOfYear.ToString("000");
new DateTime(2012, 2, 1).DayOfYear.ToString("000");
new DateTime(2012, 12, 31).DayOfYear.ToString("000");
new DateTime(2011, 12, 31).DayOfYear.ToString("000");

Answer 2

No; that's not listed.
Sorry.

Answer 3

I needed a way to allow users to give a format that could handle the day of the year and I came up with the following code.

public static string FormatDate(this DateTime date, string format)
{
    var builder = new StringBuilder();
    int numOfjs = 0;
    bool escaped = false;
    foreach (char c in format)
    {
        if (c == 'j' && !escaped)
        {
            numOfjs++;
        }
        else
        {
            if (c == 'j' && escaped)
            {
                builder.Remove(builder.Length - 1, 1);
            }

            if (numOfjs > 0)
            {
                var dayOfYearFormat = new string('0', Math.Min(3, numOfjs));
                builder.Append(date.DayOfYear.ToString(dayOfYearFormat));
            }

            numOfjs = 0;
            builder.Append(c);
        }

        escaped = c == '\\' && !escaped;
    }

    if (numOfjs > 0)
    {
        var dayOfYearFormat = new string('0', Math.Min(3, numOfjs));
        builder.Append(date.DayOfYear.ToString(dayOfYearFormat));
    }

    return date.ToString(builder.ToString());
}

This allows you to have a format that will replace consecutive un-delimited letter j's with the day of the year. It will zero pad up to 3 digits based on the number of j's. More than 3 consecutive j's act like just 3.

It basically rewrites the format to replace delimited j's with just a j, and consecutive j's with the day of the year. It then passes this new format to DateTime.ToString().

Answer 4

I know this is a bit old, but if you absolutely, positively, have to do it in one line of code without access to the DateTime.DayOfYear function (like I had to do today):

int myDay = floor(Now() - Date(parseInt(Now().ToString("yyyy")), 1, 1)) + 1;