C# Online Compiler | .NET Fiddle

<no name> by Anonymous

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		ICollection<string> list = new List<string>() {"foo", "bar"};
		
		list.Add("test");
		Console.WriteLine(list.First());
		Console.WriteLine(list.LastOrDefault());
	}
}

​x
 
using System;
using System.Linq;
using System.Collections.Generic;
​
public class Program
{
    public static void Main()
    {
        ICollection<string> list = new List<string>() {"foo", "bar"};
        
        list.Add("test");
        Console.WriteLine(list.First());
        Console.WriteLine(list.LastOrDefault());
    }
}

Sum of Area Circle= 1445.1326206513
Sum of Area Square = 964
Run-time exception (line 75): Object reference not set to an instance of an object.

Stack Trace:

[System.NullReferenceException: Object reference not set to an instance of an object.]
at JilFrühwirt.FilehandlingAndShapeReading.calculateNeighbor() :line 75
at JilFrühwirt.FilehandlingAndShapeReading.Main(String[] args) :line 66

Last Run:	3:47:26 pm
Compile:	0.11s
Execute:	0.016s
Memory:	48kb
CPU:	0.016s

View IL Code