LINQ Interview Question #65

What does Distinct do in LINQ?

Joins, Grouping, Set & Quantifier Operators Mid-Level Intermediate

Quick Interview Answer

Distinct removes duplicate elements according to the applicable equality comparison. For primitive values this is usually straightforward.

Detailed Explanation

Distinct removes duplicate elements according to the applicable equality comparison. For primitive values this is usually straightforward.

For custom objects, equality semantics determine whether two instances count as duplicates. DistinctBy can be convenient when uniqueness should be based on a selected key.

Code Example

var numbers = new[] { 1, 1, 2, 2, 3 };

var unique = numbers.Distinct();

// 1, 2, 3