Efficiently merge string arrays in .NET, keeping distinct values

c# linq arrays merge distinct
Jason Anderson picture Jason Anderson · Sep 28, 2008 · Viewed 48.6k times · Source

I'm using .NET 3.5. I have two string arrays, which may share one or more values:

string[] list1 = new string[] { "apple", "orange", "banana" };
string[] list2 = new string[] { "banana", "pear", "grape" };

I'd like a way to merge them into one array with no duplicate values:

{ "apple", "orange", "banana", "pear", "grape" }

I can do this with LINQ:

string[] result = list1.Concat(list2).Distinct().ToArray();

but I imagine that's not very efficient for large arrays.

Is there a better way?

Answer

Wonko picture Wonko · Sep 29, 2008 
string[] result = list1.Union(list2).ToArray();

from msdn: "This method excludes duplicates from the return set. This is different behavior to the Concat(TSource) method, which returns all the elements in the input sequences including duplicates."

Related questions

How do I concatenate two arrays in C#?

int[] x = new int [] { 1, 2, 3}; int[] y = new int [] { 4, 5 }; int[] z = // your answer here... Debug.Assert(z.SequenceEqual(new int[] { 1, 2, 3, 4, 5 })); Right now I use int[] z = x.Concat(y).ToArray(); Is there an easier or more efficient method?

Read More
printing all contents of array in C#

I am trying to print out the contents of an array after invoking some methods which alter it, in Java I use: System.out.print(Arrays.toString(alg.id)); how do I do this in c#?

Read More
Find index of a value in an array

Can linq somehow be used to find the index of a value in an array? For instance, this loop locates the key index within an array. for (int i = 0; i < words.Length; i++) { if (words[i].IsKey) { keyIndex = i; } }

Read More