Problem with "33 Code Project" (Chapter: Methods) / C#-Tutorial

Question

Hey there! :-)

I recently tried to solve "33 Code Project" (Chapter: Methods) while working on the C#-tutorial.

Here's my solution:
------------------------------------------------------------------------------
using System;
using System.Collections.Generic;

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
int levels = Convert.ToInt32(Console.ReadLine());

Console.WriteLine(Points(levels));

Console.ReadLine();
}

static int Points(int anzahlLevel)
{
int[] myArray = new int[anzahlLevel];
int arrayIndex = 0;

while (arrayIndex < anzahlLevel)
{
myArray[arrayIndex] = ++arrayIndex;
}

int sumLevel = myArray.Sum();
return sumLevel;
}
}
}
------------------------------------------------------------------------------
I always tried to solve the exercises "my way" and it has never been a problem before.
This time I got the following error message:

"usercode/file0.cs(27,36): error CS1061: 'int[]' does not contain a definition for 'Sum' and no accessible extension method 'Sum' accepting a first argument of type 'int[]' could be found (are you missing a using directive or an assembly reference?)"

My code worked just fine in Visual Studio and the output was correct, too.
Could you please tell me what I did wrong? :-/

Thanks in advance! ^-^

Answer 1

you need to import Linq to use Sum()
add:

using System.Linq;

Answer 2

Bahha🐧 Thank you! ☺️