Extending and filtering C# arrays

Question

I have been doing a lot of List<SomeType> - > SomeType[] conversion lately, especially when I'm filtering or extending arrays.

For example filtering:

// filter the list
var memberList = new List<MemberType>();
foreach (var member in members)
{
    if (member.someProperty != sentinalValue)
    {
        memberList.Add(member);
    }
}
// overwrite the old array with a new on dimensioned correctly
members = new MemberType[memberList.Count];
memberList.CopyTo(members);

or extending:

// create the new member
var newMember = new MemeberType();
// create a new array to hold the extended members
newMembers = new MemberType[members.Length + 1];
// copy over the old members
members.CopyTo(newMembers, 0);
// add the new member
newMembers[members.Length] = newMember;
// overwrite old array with new array containing new member
members = newMembers;

I have to use arrays (MemberType[]) instead of a nice generic collection because of the XML Serialization classes we use. I feel confident there is a nicer way to do this simple sort of thing so if you know of one (that doesn't add undue complexity) let me know.

Answer 1

There are extension methods to do exactly what you've described:

var membersList = members.ToArray();

Answer 2

members = memberList.Where(m => m.someProperty != sentinelValue).ToArray();

members = members.Concat(new[] { newMember }).ToArray();