Check if all items are the same in a List
I created simple extension method mainly for readability that works on any IEnumerable.
if (items.AreAllSame()) ...
And the method implementation:
/// <summary>
/// Checks whether all items in the enumerable are same (Uses <see cref="object.Equals(object)" /> to check for equality)
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="enumerable">The enumerable.</param>
/// <returns>
/// Returns true if there is 0 or 1 item in the enumerable or if all items in the enumerable are same (equal to
/// each other) otherwise false.
/// </returns>
public static bool AreAllSame<T>(this IEnumerable<T> enumerable)
{
if (enumerable == null) throw new ArgumentNullException(nameof(enumerable));
using (var enumerator = enumerable.GetEnumerator())
{
var toCompare = default(T);
if (enumerator.MoveNext())
{
toCompare = enumerator.Current;
}
while (enumerator.MoveNext())
{
if (toCompare != null && !toCompare.Equals(enumerator.Current))
{
return false;
}
}
}
return true;
}
Like this:
if (list.Distinct().Skip(1).Any())
Or
if (list.Any(o => o != list[0]))
(which is probably faster)
My variant:
var numUniques = 1;
var result = list.Distinct().Count() == numUniques;