list.RemoveAt in loop

Question

for (int j = 0; j < list.Count; ++j )
{
     if (list[j].current_status == false)
     {  
       list.RemoveAt(j);  
     }  
}

I want to remove all the items which has current_status == false in the list, However, When execute the statement: list.RemoveAt(j), the list.Count will minus one. Finally, the original loop can not be looped from list[0] to list[list.Count]. How can I deal with this situation?

Thanks

score 6 · Answer 1 · answered Sep 10 '14 at 03:07

6

You could use RemoveAll instead of RemoveAt:

list.RemoveAll(item => item.current_status == false);

answered Sep 10 '14 at 03:07

Jon

16,212
8
50
62

This is much better than the original loop idea because it runs in linear time. – Ben Voigt Sep 10 '14 at 03:12

score 0 · Accepted Answer · answered Sep 10 '14 at 03:07

0

int size = list.Count;
for (int j = 0; j < size; ++j )
{
   if (list[j].current_status == false)
   {  
      list.RemoveAt(j);  
      size--;
      j--;
   }  
}

answered Sep 10 '14 at 03:07

LVBen

2,041
13
27

score 0 · Answer 3 · answered Sep 10 '14 at 03:23

Also running linear time, a reverse loop like so:

for (int j = length - 1; j >= 0; j--)
{
    if (!list[j].current_status)
    {  
        list.RemoveAt(j);
    }
}

Side note : try not to test booleans with "==" and/or "!=" but use the expression itself or the negation symbol is needed

list.RemoveAt in loop

3 Answers3