CODEWITHSUNDEEP
c#.netarraysc#-3.0generics
ludicode
ludicode

Reputation: 11

To Experts: What's The Difference In This Code?

I ask this because I got an error "ArgumentOutOfRange" using the generic form.

  List<WaitHandle> arraywaithandles = new List<WaitHandle>(4);

or...

    WaitHandle[] A = new WaitHandle[4]

This works:

       for (int i = 0; i < 4; i++)
        {
            A[i] = (arrayresultados[i].AsyncWaitHandle);
        }

This does not work:

       for (int i = 0; i < 4; i++)
        {
            arraywaithandles[i] = (arrayresultados[i].AsyncWaitHandle);
        }

Upvotes: 1

Views: 134

Answers (3)

Dean Chalk
Dean Chalk

Reputation: 20451

try this

List<WaitHandle> arraywaithandles = 
    Enumerable.Repeat<WaitHandle>(null, 4).ToList();

Upvotes: 0

In silico
In silico

Reputation: 52149

This:

new List<WaitHandle>(4);

creates a List object that has an initial capacity of 4 WaitHandles. What that means is that the List after the above line will hold zero WaitHandles, but has at least enough memory to receive 4 WaitHandles without having to perform an extra memory allocation later.

This way, if you know you will need to insert 200 WaitHandles but don't actually have them right now, you can have the List object allocate enough memory for 200 WaitHandles in one go instead of having to reallocate as you add WaitHandles.

That's why your first for loop threw an ArgumentOutOfRange exception because you tried to access non-existing WaitHandles in arraywaithandles. If you need to add WaitHandles to the List, then you would use the aptly named List<T>::Add() method.

This, on the other hand:

new WaitHandle[4];

creates an array of 4 WaitHandles that will be in existence by the time the above line finishes.

Upvotes: 7

Eric K Yung
Eric K Yung

Reputation: 1784

You want to try this instead:

for (int i = 0; i < 4; i++)
{
    arraywaithandles.Add(arrayresultados[i].AsyncWaitHandle);
}

Upvotes: 2

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