Part 29 - Concat operator in LINQ

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Part 26 - Set operators in LINQ
Part 27 - Union, Intersect and Except operators in LINQ
Part 28 - Generation Operators in LINQ



In this video we will discuss
1. The use of Concat operator
2. Difference between Concat and Union operators



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);

}

Output :


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);

}

Output :


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.