Better way to remove matched items from a list

Question

In c#, when I want to remove some items from a list, i do it in the following way,

List<Item> itemsToBeRemoved = new List<Item>();
foreach(Item item in myList)
{
   if (IsMatching(item)) itemsToBeRemoved.Add(item);
}

foreach(Item item in itemsToBeRemoved)
{
   myList.Remove(item);
}

Is there any better way to do it?

Answer 1

Well, you could call the method that does exactly what you want.

myList.RemoveAll(IsMatching);

Generally it is "better" to use the method that does exactly what you want rather than re-inventing it yourself.

Answer 2

myList.RemoveAll(x=> IsMatching(x));

Answer 3

Here's a bit of an improvement using Linq.

var itemsToRemove = myList.Where(item => IsMatching(item)).ToList();
foreach(Item item in itemsToBeRemoved)
{
   myList.Remove(item);
}

Answer 4

How about reverting your logic, adding items which doesn't match and just use the result collection?

List<Item> itemsTaken = new List<Item>();
foreach(Item item in myList)
{
   if (!IsMatching(item)) itemsTaken.Add(item);
}

// use itemsTaken as if it were myList with items removed

Answer 5

What I used to do is the create a reverse for-loop:

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

But I'm sure there are more elegant ways using LINQ.

Answer 6

Similar to what Jakers said, and assuming you are on .Net 3:

myList = myList.Where(item => !IsMatching(item)).ToList();

Answer 7

foreach(Item singleItem in new List<Item>(allItems))
{
  if(IsMatching(singleItem))
     allItems.Remove(singleItem);
}