Question

Consider this:

string test = "";
somestring.ToList().Take(50).Select(
    delegate(char x)
    {
        test += x;
        return x;
    }
);

Why is test empty after that? I don’t care about the return of that actually (I know its IEnumerable<string>).

If this is all seems a mess then how can I convert the IEnumerable<char>
returned by Select() to string ?

Answer 1

Because you didn’t execute the query. Linq is lazy. It will be executed when you do either foreach or ToList/ToArray/ToDictionary.

and i advice to do it like that

string test = new string(somestring.Take(50).ToArray());

or even using

string test = somestring.Substring(0, 50);

More on that. Select is intended to apply some kind of transformation to every element in sequence. This operation is also known as map. If you want to produce single element from sequence it is Aggregate, aka reduce. It is not lazy, it forces execution of query.