how a var type can be an array without [ ] ?

Hi Armin, well its best question,  var is not a type, it's just a syntactic sugar for implicit type definition.

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/implicitly-typed-local-variables 

You need to specify your array type:    var array = new YourType[counter];

With using var you let the compiler to infer the type. But in this case it works like a shortcut.Anyway it's useful when you are not sure about the returning type of an expression or method (for example it's useful when using LINQ) :    var array = new[counter];

In this line if you mean to create an array that can contains any type of element you can create an array of objects or dynamic:

var array = new object[counter];

Or:

var array = new dynamic[counter];