Remove specific objects from a list

I have a class that has an list<Book> in it, and those Book objects has many many properties. How can I remove from that list every Book that his 开发者_运维技巧level value is different than, for example, 5?

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In this particular case, List<T>.RemoveAll is probably your friend:

C# 3:

list.RemoveAll(x => x.level != 5);

C# 2:

list.RemoveAll(delegate(Book x) { return x.level != 5; });

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list.RemoveAll(bk => bk.Level != 5);

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list.RemoveAll(delegate(Book b) { return b.Level == 5; });

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Although List.RemoveAll() is an excellent solution, it does a "foreach" on the collection resuling in O(n) or worse performance. If you have lots of items in the list, i would suggest checking out Erick's Index 4 Objects collections.

See http://www.codeplex.com/i4o