Exercises and solutions for the fifth day.
Implement a multithreaded program. One thread, the worker thread, is doing some time consuming "work" (i.e. counts to infinity or calculates all prime numbers up to a maximum value) and reports periodically its progress (e.g. every new prime number) to another thread, the UI thread.
One last thing: Avoid cross-threading exceptions!
Write a simple math tool that let's users enter numbers in two textboxes. Only integer numbers separated by commas should be allowed. Place all user controls in a TabControl.
There should be one ComboBox element and one Button control. The combobox contains the following strings:
- Intersection
- Union
- Except
- Symmetric Except
- Square
- Square Root
- Sum
- Min
- Max
If the button is pressed a function is called depending on the currently selected item in the combobox. While the first four functions are requiring both sets of numbers (obtained from the two textboxes), the other functions only require one of the sets.
It should be obvious that each function represents a LINQ function. The result of the LINQ operation should be displayed in a new tab (called results) of your form.
Compute the following method in an async task and await the result:
double ComputePi()
{
var sum = 0.0;
var step = 1e-9;
for(var i = 0; i < 1000000000; i++)
{
var x = (i + 0.5) * step;
sum = sum + 4.0 / (1.0 + x * x);
}
return sum * step;
}
Start the computation by presing a button. The button click event handler should then disable the button, await the result of the computation, set the result of the computation in a label and enable the button again.
Use the Task Parallel Library to make a parallel version of the method given in exercise 23. Try to avoid race conditions, i.e. synchronize the communication on shared variables. Reduce the required communication where possible and reduce the usage of shared variables to a minimum. Compare executation time and result with the serial implementation.
Hint Use Parallel.For instead of for and take the overload that defines a (thread-)local variable as well.
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