Linq- Concat operator

Concat operator concatenates two sequences into one sequence.

The following code will concatenate both the integer sequences (numbers1 & numbers2) into one integer sequence. Notice that the duplicate elements ARE NOT REMOVED.

int[] numbers1 = { 1, 2, 3 };

int[] numbers2 = { 1, 4, 5 };

var result = numbers1.Concat(numbers2);

foreach (var v in result)

{

    Console.WriteLine(v);

}

Now let us perform a union between the 2 integer sequences (numbers1 & numbers2). Just like concat operator, union operator also combines the 2 integer sequences (numbers1 & numbers2) into one integer sequence, but notice that the duplicate elements ARE REMOVED.

int[] numbers1 = { 1, 2, 3 };

int[] numbers2 = { 1, 4, 5 };

var result = numbers1.Union(numbers2);

foreach (var v in result)

{

    Console.WriteLine(v);

}

What is the difference between Concat and Union operators?
Concat operator combines 2 sequences into 1 sequence. Duplicate elements are not removed. It simply returns the items from the first sequence followed by the items from the second sequence. 

Union operator also combines 2 sequences into 1 sequence, but will remove the duplicate elements.

Posted in: LINQ