默认情况下，DateTime.Now 是否总是返回 24 小时格式？

Question

Currently it is evening and couldn't actually test it with morning hours like 7 in the morning. but a code like this:

DateTime dt = DateTime.Now;
string str = dt.ToString("HH:mm");

So my question is can I be sure that it is always returning time in format like "07:35" and not "7:35" ?

Answer 1

DateTime.Now returns time without formatting. Format applied in the ToString("HH:mm") method. And yes, this format is 24-hour.

Answer 2

Yes because the documentation says:

The "HH" Custom Format Specifier : The "HH" custom format specifier (plus any number of additional "H" specifiers) represents the hour as a number from 00 through 23; that is, the hour is represented by a zero-based 24-hour clock that counts the hours since midnight. A single-digit hour is formatted with a leading zero.

Answer 3

You could test with

DateTime dt = DateTime.Now;
string str = dt.ToString("HH:mm");
Console.WriteLine(str);
DateTime t = new DateTime(2014,3,27,7,5,0);
str = t.ToString("H:mm");
Console.WriteLine(str);

The HH format return always the hour formatted with two digits adding a leading zero when the hour is less than 10, the H format returns the hours formatted with exactly the digits present in the hour part.

Answer 4

You can create an instance of DateTime with desired date and time values using to test various time setting and formats :

var dt = new DateTime(2014, 1, 1, 7, 35, 0);
string str = dt.ToString("HH:mm");