I have a list that some of its members are ""so I want to remove them and I used foreach and mylist.remove(elements) but after one iteration it doesn't work and I think the problem is in changing the size of the list
foreach (string element in list)
{
if (element=="")
{
list.Remove(element);
}
}
You can use System.Linq, as so:
list = list.Where(x => x != "").ToList();
Or, if you also want to remove those elements which equal NULL, use the below:
list = list.Where(x => !string.IsNullOrEmpty(x)).ToList();
If you want to do it without Linq, you can.
for (int i = 0; i < list.Count; i++)
{
if (string.IsNullOrEmpty(element))
{
list.RemoveAt(i);
i--;
}
}
Short Answer: You do not.
Long Answer: foreach does not work with collections, it only works with Enumerators. Luckily every collection and their dog can be converted into a Enumerator. It just did that implicitly without you even noticing it.
However one standing rule of Enumerators that should always be followed is: if the underlying collection changes, the Enumerator must become invalid.
https://learn.microsoft.com/en-us/dotnet/api/system.collections.ienumerator?view=netframework-4.8
"If changes are made to the collection, such as adding, modifying, or deleting elements, the behavior of the enumerator is undefined. "
And just to be certain to not cause any issues, most Enumerators just throw an Exception.
Edit: Linq Solutions
The Linq Solutions posted by others get around that. While it propably uses a foreach (IIRC the linq expression actually is a enumerator), it does not change the list. It just creates a new list with the elements you filtered for. None of the headache, but linq can cause memory issues in extreme or fringe cases (large lists, webapplications) - just in case you need to mind your memory profile.
Use List<T>.RemoveAll() to do an in-place remove that does not involve creating a new list:
list.RemoveAll(element => element == "");
Or if elements can be null and you also want to remove them:
list.RemoveAll(element => element == null || element == "");
or (shorter and more self-descriptive):
list.RemoveAll(string.IsNullOrEmpty);
