How to Abort completed tasks

Question

Hi!

How do I abort completed tasks. I have used the following code: -

class Program

{

static void Main(string[] args)

{

System.Timers.Timer myTimer = new System.Timers.Timer();

myTimer.Elapsed += new ElapsedEventHandler(OnTimer);

myTimer.Interval = 1000;

myTimer.Enabled = true;

myTimer.AutoReset = false;

Console.WriteLine(@"Press 'q' and 'Enter' to quit...");

while (Console.Read() != 'q')

{

Thread.Sleep(1000);

}

}

public static void OnTimer(Object source, ElapsedEventArgs e)

{

System.Threading.Tasks.Task[] tasks = new System.Threading.Tasks.Task[10];

for(int i=0; i<10; i++)

{

if (tasks[i] != null && (tasks[i].Status == TaskStatus.Running || tasks[i].Status == TaskStatus.WaitingToRun || tasks[i].Status == TaskStatus.WaitingForActivation))

{

Console.WriteLine("Task has attempted to start while already running");

}

else

{

Console.WriteLine("Task {0} has begun", i);

Thread.Sleep(1000);

}

if (tasks[i].Status == TaskStatus.RanToCompletion)

{

Console.WriteLine("\n\n\t");

Console.WriteLine("Task{0} has completed", i);

}

}

Console.WriteLine();

Console.WriteLine();

System.Timers.Timer theTimer = (System.Timers.Timer)source;

theTimer.Interval += 1000;

theTimer.Enabled = true;

}

}

The moment the control reaches on the condition if(tasks[i].Status == TaskStatus.RanToCompletion) it throws an error "Object reference not set to an instance of an object". Can anyone tell me what's wrong with this code.

Second thing, how do i abort the completed tasks?