.NET - Remove from a List<T> within a 'foreach' loop

Question

I have code that I want to look like this:

List<Type> Os;  ...  foreach (Type o in Os)     if (o.cond)         return;  // Quitting early is important for my case!     else         Os.Remove(o);  ... // Other code 

This doesn't work, because you cannot remove from the list when you are inside a foreach loop over that list:

Is there a common way to solve the problem?

I can switch to a different type if needed.

Option 2:

List<Type> Os;  ...  while (Os.Count != 0)      if (Os[0].cond)          return;      else          Os.RemoveAt(0);  ... // Other code 

Ugly, but it should work.

Answer 1

You can iterate through the list backwards:

for (int i = myList.Count - 1; i >= 0; i--) {     if (whatever) myList.RemoveAt(i); } 

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In response to your comment about wanting to quit when you find an item that you're NOT removing, then just using a while loop would be the best solution.

Answer 2

You should never remove anything from a collection you are iterating over while inside of a foreach loop. It's basically like sawing the branch you are sitting on.

Use your while alternative. It is the way to go.