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{TOC}

Back to Standard Query Operator Index


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Introduction

The Union operator produces the set union of two sequences.

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Method Signatures

// 1 - Returns elements which appear in both sequences.
public static IEnumerable<TSource> Union<TSource>(IEnumerable<TSource> first, IEnumerable<TSource> second)
 
// New in January CTP
// 2 - Returns elements which appear in both sequences, using a custom comparer function
public static IEnumerable<TSource> Union<TSource>(IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)
 

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Exceptions

Throws an ArgumentNullException if first or second is null.


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Pseudo-code

Overload 1
If first is null, throw an ArgumentNullException.
If second is null, throw an ArgumentNullException.
Create a collection to hold elements we have already returned.
Iterate the source sequence.

Overload 2
If first is null, throw an ArgumentNullException.
If second is null, throw an ArgumentNullException.
If comparer is null, set the comparer to EqualityComparer<TElement>.Default.
Iterate the source sequence.

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Loop count

This operator implements the standard deferred execution iterator pattern. This means, no looping will occur until the result is iterated over.

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Code Samples

TODO: Needs code sample.