C# string interpolation with variable format

Question

I need to format a variable with string interpolation, and the format string is another variable:

here is my sample code:

static void Main(string[] a         


        

Answer 1

I have tested this piece of code and it seems to work:

static void Main(string[] args)
{
    int i = 12345;

    Console.WriteLine("Test 1: {0:N5}",i);

    var formatString = "N5";

    Console.WriteLine("Test 2: {0:" + formatString + "}", i);

    Console.ReadLine();
}