C# - .Select(int.Parse), compiler error cs0411

Question

I've just read this question: Convert string[] to int[] in one line of code using LINQ

There was an array of strings:

var arr = new string[] { "1", "2", "3", "4" };

And one of the accepted answers was:

int[] myInts = arr.Select(int.Parse).ToArray();

I tried it myself and received a cs04011 compiler error:

string str = "4 8 15 16 23 42";
int[] intArray = str.Split(' ').Select(int.Parse).ToArray();

Here's page, describing this compiler error: MSDN

If I do it this way, it works fine:

int[] intArray = str.Split(' ').Select(p=>int.Parse(p)).ToArray();

I'm wondering, why did the accepted asnwer for the previous question worked fine and I get an error?

My guess is that my visual studio (2008 express, targeted framework = 3.5) is no good, but I failed to find any proofs.

Thanks in advance!

Answer 1

The short answer is: C# type inference and support for method group conversions has improved over time. You're still using the C# 3 compiler (which is what shipped in VS 2008). The exact details are tricky, and I can never remember exactly what changed in the specification - type inference is one of the hairier bits of the spec, and it doesn't quite describe the intended behaviour quite correctly anyway, as far as I'm aware.

If you use a more recent compiler following more recent language rules, it'll be fine. This doesn't depend on the version of the framework you're targeting - only the compiler/language version is relevant here.

I'd strongly recommend upgrading straight to Visual Studio 2015 - C# 6 has some lovely features for removing cruft from your code...