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C# Querying With LINQ Query Operators Set Operations

Aaron Selonke
Aaron Selonke
10,323 Points
Posted by Aaron Selonke
Aaron Selonke
10,323 Points

Difference between Union() and Concat()

What's the difference between using Union and Concat, they seem to produce the same sequence?

It seems like colors.Concat(birds.Select(i => i.Color).Distinct()); and colors.Union(birds.Select(i => i.Color)); are the same

but Carling still uses the .Distinct() when using Union() .... ? It seems like Union() already produces a distinct color sequence and that is the difference.

1 Answer

Steven Parker
Steven Parker
229,608 Points
Steven Parker
Steven Parker
229,608 Points

You're right, you don't need Distinct when you use Union. It doesn't hurt, but it doesn't need to be there.

And, that's basically the difference between Union and Concat. With Union you get no duplicates, but with Concat you may.