CODEWITHSUNDEEP
c#delegates
Abdul Khaliq
Abdul Khaliq

Reputation: 2463

Anonymous C# delegate within a loop

Hi all I am trying to write and anonymous delegate. as the integer variable is shared among the delegate I need it to be the local instance of every delegate such that rs[0] always gets nics[0], rs[1] always gets nics[1] and so on... how will I achieve this.

for (int i = 0; i < nics.Count; i++)
{
    rs[i] = new RollingSeries(monitor, new RollingSeries.NextValueDelegate(delegate()
    {
        return GetNetworkUtilization(nics[i]);
    }));
}

Upvotes: 14

Views: 7654

Answers (3)

Heinzi
Heinzi

Reputation: 172478

Put int j = i inside your loop and refer to j within the lambda expression.

If you are curious about why this happens, here is an MSDN blog entry containing a detailed technical explanation: Closing over the loop variable considered harmful

Upvotes: 4

JaredPar
JaredPar

Reputation: 755587

Use a local to get a different value per iteration

for (int i = 0; i < nics.Count; i++)
   {
         int localI = i;
         rs[i] = new RollingSeries(monitor, new RollingSeries.NextValueDelegate(delegate()
         {
            return GetNetworkUtilization(nics[localI]);
          }));
    }

Upvotes: 6

bruno conde
bruno conde

Reputation: 48255

Make a local copy of i:

   for (int i = 0; i < nics.Count; i++)
   {
         int j = i;
         rs[i] = new RollingSeries(monitor, new RollingSeries.NextValueDelegate(delegate()
         {
            return GetNetworkUtilization(nics[j]);
          }));
    }

The Beauty of Closures

Upvotes: 23

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