would remove a key from Dictionary in foreach cause a problem? or should I better to construct a new Dictionary?

Question

for example:

1.

         foreach (var item in myDic)
                {
                  if (item.value == 42)
                        myDic.remove(item.         


        

Answer 1

I would suggest making a copy of the keys and not the entire dictionary as an array, like others have suggested.

mykeytype[] mykeys = new mykeytype[mydic.Keys.Count];
mydic.Keys.CopyTo(mykeys, 0);
foreach (var key in mykeys)
{
    MyType thing;
    if (!mydic.TryGetValue(key, out thing)) continue;

    // remove or add to dictionary here
}