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rounding to a specific 12hr timeframe in c#.net

I realize this may have been answered before, and I may just not be searching for the answer properly, so my apologies if this is a duplicate. This is for a c# webform.
I've got a datetime, set to now, and rounded up the nearest 30 minutes:
DateTime dtNow = RoundUp(DateTime.Now, TimeSpan.FromMinutes(30));
I'm splitting the datetime into its component parts, using M:YY tt (no preceding 0 on the month, two digit year, 12 hr am/pm)
DateString = dtNow.ToString("M/dd/yy");
TimeString = dtNow.ToString("h:mm tt");
What I want do to is simple, I want to see if that TimeString falls between 7:00pm and 5:59am, just need to round it to 6:00am of the following day (unless its past midnight, in which case 6:00am of that day).
Can anyone help me out, or at least point out where its already answered?

You should really stick to DateTime. What you want using string will always need to parse again that string into a DateTime to implement your logic.
A simple solution:
public static DateTime GetRoundedDate(DateTime originalDate)
{
if(originalDate.Hour > 19)
return originalDate.Date.AddDays(1).AddHours(6);
else if (originalDate.Hour < 6)
return originalDate.Date.AddHours(6);
return originalDate;
}
So now you may call:
DateTime dtNow = RoundUp(DateTime.Now, TimeSpan.FromMinutes(30));
var rounded = GetRoundedDate(dtNow);
DateString = rounded.ToString("M/dd/yy");
TimeString = rounded.ToString("h:mm tt");

Just look at the time properties on your DateTime object.
if (dtNow.Hour >= 19 || (dtNow is tomorrow && dtNow.Hour <= 7)) {
//do your stuff
}
where "is tomorrow" is something like dtNow.Date == DateTime.Today.AddDays(1)

C# - Validate an int-based DateTime without exceptions?

This question talks about validating a string representing a date, and in it folks mention that it's good to avoid using Exceptions for regular flow logic. And TryParse() is great for that. But TryParse() takes a string, and in in my case i've already got the year month and day as integers. I want to validate the month/day/year combination. For example February 30th.
It's pretty easy to just put a try/catch around new DateTime(int, int, int), but I'm wondering if there's a way to do it without relying on exceptions.
I'd also feel silly composing these ints into a string and then using TryParse().

The following will check for valid year/month/day combinations in the range supported by DateTime, using a proleptic Gregorian calendar:
public bool IsValidDate(int year, int month, int day)
{
return year >= 1 && year <= 9999
&& month >= 1 && month <= 12
&& day >= 1 && day <= DateTime.DaysInMonth(year, month);
}
If you need to work with other calendar systems, then expand it as follows:
public bool IsValidDate(int year, int month, int day, Calendar cal)
{
return year >= cal.GetYear(cal.MinSupportedDateTime)
&& year <= cal.GetYear(cal.MaxSupportedDateTime)
&& month >= 1 && month <= cal.GetMonthsInYear(year)
&& day >= 1 && day <= cal.GetDaysInMonth(year, month);
}

Use String Interpolation
int year = 2017;
int month = 2;
int day = 28;
DateTime dt;
DateTime.TryParse($"{month}/{day}/{year}", out dt);

As far as I know, there's no easy way to check for a DateTime's int's validity besides concatenating the ints into a correctly formatted string beforehand.
To avoid try/catch-ing, I would write a static utility class which utilizes DateTime.TryParse:
using System;
public static class DateTimeUtilities
{
public static bool TryParse(int year, int month, int day, out DateTime result)
{
return DateTime.TryParse(
string.Format("{0}/{1}/{2}", year, month, day), out result);
}
}
Usage:
DateTime dateTime;
if (DateTimeUtilities.TryParse(2017, 2, 30, out dateTime))
{
// success
}
else
{
// fail, dateTime = DateTime.MinValue
}
Pending the needs of your application, e.g. culture (thanks #Matt Johnson), I would also look into DateTime.TryParseExact.

Look at it this way. Any code that you write:
Will have to check month ranges 1-12
Will have to check day ranges by month, which means you'll have to hard code an array
Will have to account for leap years, which can be a pain the the rear
Rather than doing ALL that, and reinventing the wheel, and potentially getting it wrong -- why don't you keep it simple and just wrap the DateTime constructor in a try-catch and keep it moving? Let the nerds up in Redmond do all the hard work for this common task. The best solution is one that any developer following you can understand and rely upon quickly.
I'd bet money that under the hood, TryParse and the DateTime constructor are using the exact same validators, except that the latter throws an exception while the former does not. TryParse, for this, is overkill with all the extra string manipulation involved.

How can I check if current day is working day

I have application that needs to be run on working days, and within working hours.
In application configuration, I've set start time in format
Monday-Friday
9:00AM-5:30PM
Now, I have a problem how to check if current day is within day boundare is (for the time is easy - parse time with DateTime.ParseExact and simple branch will do), but I don't know how to parse days.
I've tried with:
DayOfWeek day = DateTime.Now.DayOfWeek;
if (day >= (DayOfWeek)Enum.Parse(typeof(DayOfWeek), sr.start_day) &&
day <= (DayOfWeek)Enum.Parse(typeof(DayOfWeek), sr.end_day))
{ /* OK */ }
sr.start_day and sr.end_day are strings
but the problem occurred during weekend testing - apparently, in DayOfWeek enum, Sunday is first day of the week (refering to the comments on MSDN page
I suppose I could do some gymnastics with current code, but I am looking for the most readable code available.
Edit
Sorry for the misunderstanding - working days are not from Monday to Friday - they are defined as strings in config file, and they can be even from Friday to Saturday - which breaks my original code.

if ((day >= DayOfWeek.Monday) && (day <= DayOfWeek.Friday))
{
// action
}

From Hans Passant's comment on my original question:
Just add 7 to the end day if it is less than the start day. Similarly,
add 7 to day if it is less than the start day.
DayOfWeek day = DateTime.Now.DayOfWeek;
DayOfWeek start_day = (DayOfWeek)Enum.Parse(typeof(DayOfWeek), sr.start_day);
DayOfWeek end_day = (DayOfWeek)Enum.Parse(typeof(DayOfWeek), sr.end_day);
if (end_day < start_day)
end_day += 7;
if (day < start_day)
day += 7;
if (day >= start_day && day <= end_day)
{
//Action
}

extention for DateTime
public static bool IsWeekend(this DateTime date)
{
return new[] {DayOfWeek.Sunday, DayOfWeek.Saturday}.Contains(date.DayOfWeek);
}

This is an elegant solution for the problem. It's a class that can easily be imported into other projects. The coding allows the programmer to dynamically assign what days to check for and pass them as a string array to the class. The data can come from a database or be hard coded when you pass it to an instance of this class for processing. It returns the values of True if you're off work and False if you're working that day. Below the class I provided a simple example of implementation. This class features: Dynamic allocation of what days you have off, Simple error handler by setting strings to lowercase before comparing them, Easily integrated with a database that has your work schedule where your days off may not always be the same. Easily integrated as a hard coded number of days off.
// The Class To Check If You're Off Work
class DayOffChecker
{
public bool CheckDays(List<string> DaysOff)
{
string CurrentDay = DateTime.Now.DayOfWeek.ToString();
CurrentDay.ToLower();
foreach (string DayCheck in DaysOff)
{
DayCheck.ToLower();
if (CurrentDay == DayCheck)
{
return (true);
}
}
return (false);
}
}
// Example usage code:
class Program
{
List<string> DaysOff = List<string>();
DaysOff.Add("Saturday"); // Add some values to our list.
DaysOff.Add("Sunday");
DayOffChecker CheckToday = new DayOffChecker();
if(CheckToday.CheckDays(DaysOff))
{
Console.WriteLine("You're Off Today!!!");
}
}

We can also follow similar approach of checking if a given hour is between two hours. Following is the algorithm
checkIfFallsInRange(index,start,end)
bool normalPattern = start <= end ;
if ( normalPattern)
return index>=start && index<=end;
else
return index>=start || index <=end;

My simple solution to determining if the current day is a workday or not is:
public static bool IsWorkDay(this DateTime dt)
{
return IsWorkDay(dt, DayOfWeek.Sunday, DayOfWeek.Saturday);
}
public static bool IsWorkDay(this DateTime dt, params DayOfWeek[] noneWorkDays)
{
return !noneWorkDays.Contains(dt.DayOfWeek);
}
It assumes Sunday / Saturday are non-work days. Otherwise the user can specify the non-work days. And is an extension for easy of use.
Note: To avoid a loop could created a bit flag.

DayOfWeek Day = DateTime.Today.DayOfWeek;
int Time = DateTime.Now.Hour;
if (Day != DayOfWeek.Saturday && Day != DayOfWeek.Sunday)
{
if (Time >= 8 && Time <= 16)
{
//It is Weekdays work hours from 8 AM to 4 PM
{
}
else
{
// It is Weekend
}

You can use the DayOfWeek enumeration in order to see if a date is Sunday or Saturday. http://msdn.microsoft.com/en-us/library/system.dayofweek.aspx I hope this can help.

The line below will return "Sunday"
string nameOfTheDay = DateTime.Now.ToString("dddd", new System.Globalization.CultureInfo("en-GB")).ToLower();
if(nameOfTheDay != "sunday" && nameOfTheDay != "saturday")
{
//Do Stuff
}

public bool IsWeekend(DateTime dateToCheck)
{
DayOfWeek day = (DayOfWeek) dateToCheck.Day;
return ((day == DayOfWeek.Saturday) || (day == DayOfWeek.Sunday));
}

Regular DateTime question

I'm writing a service but I want to have config settings to make sure that the service does not run within a certain time window on one day of the week. eg Mondays between 17:00 and 19:00.
Is it possible to create a datetime that represents any monday so I can have one App config key for DontProcessStartTime and one for DontProcessEndTime with a values like "Monday 17:00" and "Monday 19:00"?
Otherwise I assume I'll have to have separate keys for the day and time for start and end of the time window.
Any thoughts?
thanks

You could use a utility that will parse your weekday text into a System.DayOfWeek enumeration, example here. You can then use the Enum in a comparison against the DateTime.Now.DayOfWeek

You can save the day of the week and start hour and endhour in your config file, and then use a function similar to the following:
public bool ShouldRun(DateTime dateToCheck)
{
//These should be read from your config file:
var day = DayOfWeek.Monday;
var start = 17;
var end = 19;
return !dateToCheck.DayOfWeek == day &&
!(dateToCheck.Hour >= start && dateToCheck.Hour < end);
}

You can use DayOfTheWeek property of the DateTime.
And to check proper time you can use DateTime.Today (returns date-time set to today with time set to 00:00:00) and add to it necessary amount of hours and minutes.

The DateTime object cannot handle a value that means all mondays. It would have to be a specific Monday. There is a DayOfWeek enumeration. Another object that may help you is a TimeSpan object. You could use the DayOfWeek combined with TimeSpan to tell you when to start, then use another TimeSpan to tell you how long

This is very rough code, but illustrates that you can check a DateTime object containing the current time as you wish to do:
protected bool IsOkToRunNow()
{
bool result = false;
DateTime currentTime = DateTime.Now;
if (currentTime.DayOfWeek != DayOfWeek.Monday && (currentTime.Hour <= 17 || currentTime.Hour >= 19))
{
result = true;
}
return result;
}

How to check for valid Date in yyyyMM format

I have an internal business process that my finance dept runs. To kick it off they input a Date in the format of yyyyMM or 201009. I want to check for a valid date from that string but so far I got nothing.
I am currently exploring breaking the string up, taking the first 4 and checking that they are between 1990 and 2050(as example) and then the last 2 and checking that it is between 01 and 12.
Is there a better way?

You can use DateTime.TryParseExact to see if it can be parsed correctly:
bool isValid = false;
DateTime dateValue;
if(DateTime.TryParseExact("201009", "yyyyMM", CultureInfo.InvariantCulture,
DateTimeStyles.None, out dateValue))
{
// DateTime parsed, dateValue contains the parsed DateTime
// Can validate dateValue against business rules at this point
isValid = (dateValue <= DateTime.Now && dateValue >= DateTime.Now.AddYears(-5));
}
If you would rather get an exception, you can use DateTime.ParseExact:
// Next line throws exception if format not correct
DateTime.ParseExact("201009", "yyyyMM", CultureInfo.InvariantCulture);

You can use a regular expression:
if (Regex.IsMatch(input, #"^(199\d|20[0-5]\d)(0[1-9]|1[0-2])$")) {
// valid input between 199001 and 205912
}

I would go with DateTime.ParseExact:
DateTime d = DateTime.ParseExact("201009", "yyyyMM", System.Globalization.CultureInfo.InvariantCulture);

The problem here is that the format "yyyyMM" cannot represent a specific DateTime. So the parsing methods built in to DateTime will do you no good.
Update: Never mind; I stand corrected. DateTime.TryParseExact will work just fine (which is ironic, if you ask me); it'll interpret your string to represent the first day of the given month.
I would do what you're describing: parsing the string into the two numeric components and simply compare those values to whatever range you require them to fall within.

I'd be tempted perform this as a number range problem:
UInt32 val;
if (input.Length != 6
|| !UInt32.TryParse(input, out val)
|| val > 205012
|| val < 199001
|| val % 100 > 12
|| val % 100 == 0) {
// Invalid...
}