How to remove elements from a generic list while iterating over it?

Iterate your list in reverse with a for loop:

for (int i = safePendingList.Count - 1; i >= 0; i--)
{
    // some code
    // safePendingList.RemoveAt(i);
}

Example:

var list = new List<int>(Enumerable.Range(1, 10));
for (int i = list.Count - 1; i >= 0; i--)
{
    if (list[i] > 5)
        list.RemoveAt(i);
}
list.ForEach(i => Console.WriteLine(i));

Alternately, you can use the RemoveAll method with a predicate to test against:

safePendingList.RemoveAll(item => item.Value == someValue);

Here's a simplified example to demonstrate:

var list = new List<int>(Enumerable.Range(1, 10));
Console.WriteLine("Before:");
list.ForEach(i => Console.WriteLine(i));
list.RemoveAll(i => i > 5);
Console.WriteLine("After:");
list.ForEach(i => Console.WriteLine(i));

 foreach (var item in list.ToList()) {
     list.Remove(item);
 }

If you add ".ToList()" to your list (or the results of a LINQ query), you can remove "item" directly from "list" without the dreaded "Collection was modified; enumeration operation may not execute." error. The compiler makes a copy of "list", so that you can safely do the remove on the array.

While this pattern is not super efficient, it has a natural feel and is flexible enough for almost any situation. Such as when you want to save each "item" to a DB and remove it from the list only when the DB save succeeds.

A simple and straightforward solution:

Use a standard for-loop running backwards on your collection and RemoveAt(i) to remove elements.

Reverse iteration should be the first thing to come to mind when you want to remove elements from a Collection while iterating over it.

Luckily, there is a more elegant solution than writing a for loop which involves needless typing and can be error prone.

ICollection<int> test = new List<int>(new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10});

foreach (int myInt in test.Reverse<int>())
{
    if (myInt % 2 == 0)
    {
        test.Remove(myInt);
    }
}