LINQ Interview Question #67

What does Union do in LINQ?

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

Quick Interview Answer

Union returns the distinct elements that appear in either of two sequences. Duplicate values are removed according to the equality comparer.

Union returns the distinct elements that appear in either of two sequences. Duplicate values are removed according to the equality comparer.

It differs from Concat because Concat simply appends sequences and preserves duplicates.

var first = new[] { 1, 2, 3 };
var second = new[] { 3, 4, 5 };

var result = first.Union(second);

// 1, 2, 3, 4, 5