C# - Stopwatch (timer) loop

Question

C# - Stopwatch (timer) loop

Alexandru Teodor 91

In a VS 2019 WindowsFormsApp, using C#, I am trying to conditionlly set/start a Stopwatch timer in a loop.

Stopwatch[] timer_ = new Stopwatch[] { null, null, null, null, null, null, null };  
for (int i = 1; i <= 6; i++){  
	if (enable_timer_[i].Checked == true) {  
		 timer_[i].Start();  // <== System.NullReferenceException: 'Object reference not set to an instance of an object.'  
	}  
}

I also tried setting the "timer_" as a null List, with no success (Cannot implicitly convert type 'System.Collections.Generic.List<System.Diagnostics.Stopwatch>' to 'System.Diagnostics.Stopwatch').
I just cant figure out how to correctly initialize and start dynamic timers variable names...

Help would be apreciated :)

Thanks

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Answer 1

Viorel 122.6K

Try this:

Stopwatch[] timer_ = new Stopwatch[] { null, new Stopwatch(), new Stopwatch(), new Stopwatch(), new Stopwatch(), new Stopwatch(), new Stopwatch() };

or this:

for (int i = 1; i <= 6; i++)  
{  
   if (enable_timer_[i].Checked)   
   {  
      if( timer_[i] == null) timer_[i] = new Stopwatch( );  
      timer_[i].Start();   
   }  
}

By the way, maybe you should have a loop between i=0 and i < 6?

Alexandru Teodor 91 Reputation points

2022-07-06T08:21:10.127+00:00

Excelent. Thank you very much.

The reason I start at 1 and not 0 is because I first create a List of the checkboxes control names to use in the loop.
In my form the names of the checkboxes start at 1 (enable_timer_1, enable_timer_2 ... ) not 0.
I don't want to rename all checkboxes in the form to start at 0, unless you tell me that having that first value in the list/array with null impacts efficency.
Viorel 122.6K Reputation points

2022-07-06T08:42:14.07+00:00

I do not think that the unused null element impacts the efficiency.

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