What is the difference between Contains and Any in LINQ?

Question

What is the difference between Contains and Any in LINQ?

Answer 1

Contains takes an object, Any takes a predicate.

You use Contains like this:

listOFInts.Contains(1);

and Any like this:

listOfInts.Any(i => i == 1);
listOfInts.Any(i => i % 2 == 0); // Check if any element is an Even Number

So if you want to check for a specific condition, use Any. If you want to check for the existence of an element, use Contains.

MSDN for Contains, Any

Answer 2

Contains

Determines whether a sequence contains a specified element by using the default equality comparer.

Any

Determines whether a sequence contains any elements.

As for the documentation:

Can't seem to find to find any documentation on it.

All (most?) LINQ extension methods: here

Answer 3

Contains checks if the sequence contains a specified element.

Enumerable.Any checks if element of a sequence satisfies a condition.

Consider the following example:

List<int> list = new List<int> { 1, 2, 3, 4, 5 };
bool contains = list.Contains(1); //true

bool condition = list.Any(r => r > 2 && r < 5);

Answer 4

Another difference as mentioned here is on the performance

• Contains is O(n) for a List and O(1) for a HashSet
• Any is simply O(n)

Answer 5

Contains cares about whether the source collection is an ICollection, Any does not.

Enumerable.Contains http://referencesource.microsoft.com/#System.Core/System/Linq/Enumerable.cs#f60bab4c5e27a849

public static bool Contains<TSource>(this IEnumerable<TSource> source, TSource value)
{
    ICollection<TSource> collection = source as ICollection<TSource>;
    if (collection != null)
    {
        return collection.Contains(value);
    }
    return source.Contains<TSource>(value, null);
}

Enumerable.Any http://referencesource.microsoft.com/#System.Core/System/Linq/Enumerable.cs#6a1af7c3d17845e3

public static bool Any<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate)
{
    foreach (TSource local in source)
    {
        if (predicate(local))
        {
            return true;
        }
    }
    return false;
}