How can I start an action if the time in the datetime picker is eqaul to datetime.now?

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Hey guys, I'm new in this forum and this is my first post. I come from Germany and I'm almost 17 years old.

My problem is a little extensive.
I hava a normal WindowsFormsApplication.
There are 7 DateTimePickers where the user can set 7 different times (hh:mm:ss).
At the bottom of my program, there is a Label which should show the smallest difference between the actual time and one of the 7 user defined times.
If the difference equals 00:00:00 the program should show me a MessageBox and the label with the difference should update from 00:00:00 to the new difference with the 2nd smallest difference between the actual time and one of the 6 left user defined times.
This function I need for all 7 days of the week.

I hope, you understood. If you have any questions or a suggested solution, please write me.

Thanks for efforts.

Posted 28-Sep-15 5:58am

Tobias Wälde

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OriginalGriff 28-Sep-15 12:10pm

And?
What have you tried?
Where are you stuck?
What help do you need?

Tobias Wälde 28-Sep-15 13:02pm

Hey,
I tried to test for every DateTimePicker. But I want to show only the smalles difference in the label. So I wrote a lot of if-querys in a timer to show only the smallest difference.
How can I write the if-querys for 7 DateTimePickers?
And in my test-project when the time difference was equal 00:00:00 or less it opened a lot of MessageBoxes:

if([smallest Value of all DateTimePickers] < DateTime.Now)
{
MessageBox.Show("Notification: Time is over!");
}

How can I let the program show the messagebox only once?
How can I say the program that it should show the 2nd smallest difference?

[no name] 28-Sep-15 12:15pm

Hi Tobias
"If the difference equals 00:00:00" is dangerous, nobody guarantees that your process get enough attention to recognize that. You need to catch more information, something like "diff > 0", set a "trigger flag" and handle whether a specific time event has already been handled.

Tobias Wälde 28-Sep-15 13:05pm

Hi,

I tried this:

if([smallest Value of all DateTimePickers] < DateTime.Now)
{
MessageBox.Show("Notification: Time is over!");
}

But I get lots of MessageBoxes...

[no name] 28-Sep-15 13:19pm

"But I get lots of Message Boxes": That I would expect also...
I think you are able to solve it (this according what you post here and according to this it seems you are analyzing the problem), try a little bit harder. Handling such timer events _exactly one time _ is not that trivial as it looks on a first glance.
Regards, Bruno

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OriginalGriff · Answer 1 · 2015-09-28T08:09:00

Solution 1

"I tried to test for every DateTimePicker. But I want to show only the smalles difference in the label. So I wrote a lot of if-querys in a timer to show only the smallest difference.
How can I write the if-querys for 7 DateTimePickers?"

Don't! :laugh: way, way too many combinations.
So...set up an array of TimeSpan values, and load it with the 7 DateTimePicker values minus the current dateTime:

C#

DateTime now = DateTime.Now;
Timespan[] diffs = new TimeSpan[7];
diffs[0] = dateTimePicker1.Value - now;
diffs[1] = dateTimePicker2.Value - now;
diffs[2] = dateTimePicker3.Value - now;
diffs[3] = dateTimePicker4.Value - now;
diffs[4] = dateTimePicker5.Value - now;
diffs[5] = dateTimePicker6.Value - now;
diffs[6] = dateTimePicker7.Value - now;

Then use Array.Sort and you have the maximum and minimum easily available.

C#

Array.Sort(diffs);
Timespan min = diffs[0];
Timespan max = diffs[6];

(Obviously, I wouldn't use "magic numbers" in the real world)

And only ever read the time once in a method: it changes outside your control, so even doing this:
DateTime now1 = DateTime.Now;
DateTime now2 = DateTime.Now;

C#

if (now1 != now2) throw new ApplicationException("The time changed!");

Sometimes, you will get an exception, and sometimes you won't...and they can seem very different - different millenium if you do it at the wrong time! :laugh:

Posted 28-Sep-15 8:09am

OriginalGriff

Comments

Tobias Wälde 29-Sep-15 2:22am

Hey, thanks a lot for your answer.
But I have a question:
Where should I set the first code?
Should I write the code into a running timer?

OriginalGriff 29-Sep-15 3:21am

If you want it to execute repeatedly, then yes...

And it's all code you need together, not separate chunks - I separated them so you could see what did what more easily.

Tobias Wälde 29-Sep-15 11:58am

Ok, my program runs perfectly.
But I want to test for the DateTimePickers which are activated.
This is my actual code:

<pre lang="c#">private void timer_Tick(object sender, EventArgs e)
{
DateTime now = DateTime.Now;
TimeSpan[] diffs = new TimeSpan[7];

if(dateTimePicker1.Checked)
diffs[0] = now - dateTimePicker1.Value;
if(dateTimePicker2.Checked)
diffs[1] = now - dateTimePicker2.Value;
if(dateTimePicker3.Checked)
diffs[2] = now - dateTimePicker3.Value;
if(dateTimePicker4.Checked)
diffs[3] = now - dateTimePicker4.Value;
if(dateTimePicker5.Checked)
diffs[4] = now - dateTimePicker5.Value;
if(dateTimePicker6.Checked)
diffs[5] = now - dateTimePicker6.Value;

Array.Sort(diffs);
TimeSpan max = diffs[0];
TimeSpan min = diffs[6];

this.lab_timeLeft.Text = (min.Hours * (-1)).ToString("00") + ":" + (min.Minutes * (-1)).ToString("00") + ":" + (min.Seconds * (-1)).ToString("00");
}</pre>

By the way, how can I paste the code as 'Code' and not as 'Text'?

Richard Deeming 29-Sep-15 15:07pm

Since you don't know how many elements you'll be dealing with, try using a List<TimeSpan> instead of the array:


DateTime now = DateTime.Now;
List<TimeSpan> diffs = new List<TimeSpan>(7);

if (dateTimePicker1.Checked) diffs.Add(dateTimePicker1.Value - now);
if (dateTimePicker2.Checked) diffs.Add(dateTimePicker2.Value - now);
if (dateTimePicker3.Checked) diffs.Add(dateTimePicker3.Value - now);
if (dateTimePicker4.Checked) diffs.Add(dateTimePicker4.Value - now);
if (dateTimePicker5.Checked) diffs.Add(dateTimePicker5.Value - now);
if (dateTimePicker6.Checked) diffs.Add(dateTimePicker6.Value - now);

// Make sure at least one is selected:
if (diffs.Count == 0) return;

diffs.Sort();
TimeSpan min = diffs[0];
TimeSpan max = diffs[diffs.Count - 1];

this.lab_timeLeft.Text = min.ToString("c");

If you're going to negate the value at the end, you might as well swap the order of the operands in the subtraction: picker - now is the same as -(now - picker).

Using the TimeSpan's format specifier[^] is easier than formatting and combining the individual parts.

NB: If it's not already there, you might need to add using System.Collections.Generic; to the top of your code file.

Tobias Wälde 1-Oct-15 0:51am

Hey,
thanks a lot for your informations. My programm is running nearly perfectly now. But I want to set three notification times. This is my actual code:
[code]
How can I write a function where my program can view a MessageBox when the left time is e.g. at 10 minutes?

I tried this:

TimeSpan zero = new TimeSpan(0, 0, 0, 0, 0);
TimeSpan notification1 = new TimeSpan(0, 0, 10, 0, 0); //10mins

if(dateTimePicker1.Checked)
{
if((dateTimePicker1.Value – DateTime.Now) > zero)
diffs.Add(dateTimePicker1.Value – DateTime.Now);

if((dateTimePicker1.Value – DateTime.Now) < notification1)
MessageBox.Show("Notification: 10 minutes left!");
}

My problem is that I got the MessageBox 10 times per second (cause timer.Intervall = 100) if the left time is lower than 10 minutes.
How can I let the program show me the messagebox only once?

And how can I add a screenshot of my program? Because the GUI is nearly completed and so I can show you what I want to do.

OriginalGriff 1-Oct-15 5:04am

The first thing to notice is that MessageBox.Show doesn't return until the message dialog has been closed - so the simplest way to do this is add a private variable to prevent it:

private bool showingEvent = false;
Then check it in the code:

if(!showingEvent && (dateTimePicker1.Value – DateTime.Now) < notification1)
{
showingEvent = true;
MessageBox.Show("Notification: 10 minutes left!");
showingEvent = false;
}

You can't add a screenshot because the internet is full of idiots. And someone is going to think it is funny to post "inappropriate content" - which will end up with the site being blacklisted by corporate net-nannies.
Unless we moderated every single post before it was published - and with 12,000,000 members that isn't feasible - it's better to just say "no images!"
We can put images in articles and tips, but they are moderated - which takes quite a bit of time - and you would not believe the amount of spam and abusive messages get posted at the moment! If they could get images in... :shudder:

Tobias Wälde 1-Oct-15 9:55am

i tried to paste your code into the timer.
Pro: i get only one messageBox at once
Con: when the remaining time is less then 10 minutes it shows me though a messageBox but when i close the messageBox, the next box comes directly.

thats my problem...

here you can see a screenshot: https://drive.google.com/open?id=0B9TvijbG9geKUU9yMF93Q1dqNEU