CODEWITHSUNDEEP
c#linq
dragonfly02
dragonfly02

Reputation: 3659

Why does this simple LINQ expression NOT work?

This must be simple but I failed to understand why this is not allowed:

var testList = new List<int> { 2, 3, 400, 304, 50, 41 };
testList.Select(x => Console.WriteLine(x));

But this is fine: 

testList.Select(x => x * 2);

Where do I misunderstand LINQ to cause this confusion?

Upvotes: 1

Views: 158

Answers (2)

Andrew Whitaker
Andrew Whitaker

Reputation: 126042

.Select takes a Func<TSource, TResult> (a lambda that takes a TSource and returns TResult).

Since Console.WriteLine is void, your lambda does not return anything and therefore doesn't meet the requirements.

Upvotes: 8

cdhowie
cdhowie

Reputation: 168948

The problem is that the function you pass to Select() must return a value, because the purpose of Select() is to project the elements of a sequence into some other value. But Console.WriteLine(x) returns void (no value).

Upvotes: 9

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