Does .NET Offer a Built-in Way to Check if One List Contains All Elements of Another?

Does .NET Have a Built-in Method to Check if One List Contains All Items in Another?

Problem:

You have a method (ContainsAllItems) that determines if List a contains all the elements of List b. You wonder if this functionality is already built into .NET, potentially duplicating your effort.

Answer:

Yes, in .NET 3.5 and later, you can use the following method:

public static class LinqExtras
{
    public static bool ContainsAllItems<T>(this IEnumerable<T> a, IEnumerable<T> b)
    {
        return !b.Except(a).Any();
    }
}

Usage:

List<int> a = new List<int>() { 1, 2, 3, 4 };
List<int> b = new List<int>() { 2, 3 };

bool result = a.ContainsAllItems(b); // True

This method performs a set difference between b and a (b.Except(a)), which returns the elements in b that are not in a. The Any() method is then used to check if there are any elements in the set difference, and the result is inverted to determine if a contains all items in b.

Note:

The original ContainsAllItems method is also a valid solution but is slightly less efficient than the approach using LINQ. The LINQ version takes advantage of lazy evaluation, potentially performing less work if the lists have a large number of items.

The above is the detailed content of Does .NET Offer a Built-in Way to Check if One List Contains All Elements of Another?. For more information, please follow other related articles on the PHP Chinese website!