CODEWITHSUNDEEP
c#listarrays
KevinDeus
KevinDeus

Reputation: 12178

What's a quick way to convert a List<List<string>> to string[][]?

.ToArray doesn't do it

Upvotes: 8

Views: 639

Answers (3)

Jon Skeet
Jon Skeet

Reputation: 1500735

One quick variation on the existing answers, which uses a method group conversion instead of a lambda expression:

string[][] array = lists.Select(Enumerable.ToArray).ToArray();

In theory it'll be every so slightly faster, as there's one less layer of abstraction in the delegate passed to Select.

Remember kids: when you see a lambda expression of this form:

foo => foo.SomeMethod()

consider using a method group conversion. Often it won't be any nicer, but sometimes it will :)

Getting back to a List<List<string>> is easy too:

List<List<string>> lists = array.Select(Enumerable.ToList).ToList();

Upvotes: 9

luke
luke

Reputation: 14788

Linq is the way to go on this one.

List<List<String>> list = ....;
string[][] array = list.Select(l => l.ToArray()).ToArray();

to break it down a little more the types work out like this:

List<List<String>> list = ....;
IEnumerable<String[]> temp = list.Select(l => l.ToArray());
String[][] array = temp.ToArray();

Upvotes: 12

Matt Greer
Matt Greer

Reputation: 62037

List<List<string>> myStrings;

myStrings.Select(l => l.ToArray()).ToArray();

(LINQ rocks)

Upvotes: 2

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