Does list.count physically iterate through the list to count it, or does it keep a pointer

Question

I am stepping through a large list of object to do some stuff regarding said objects in the list.

During my iteration, I will remove some objects from the list depen

Answer 1

You tagged your question with both vb.net and c#, so in reply to "If .net physically re-iterates through the list, I may just as well keep a counter on my own iteration through the list, and save the overhead?"

If your iteration is with a For i = first To last then VB.NET will evaluate first and last when it enters the loop:

Dim first As Integer = 1
Dim last As Integer = 3
For i = first To last
    Console.Write(i.ToString() & " ")
    last = -99
Next

outputs: 1 2 3

If you do the equivalent in C#, first and last are evaluated on every iteration:

int first = 1;
int last = 1;
for (int i = first; i <= last; i++)
{
    Console.Write(i.ToString() + " ");
    last = -99;
}

outputs: 1

If your .Count() function/property is expensive to evaluate and/or you don't want it to be re-evaluated on each iteration (for some other reason), then in C# you could assign it to a temporary variable.