Variable alignment component in string interpolation

Question

The alignment component is the -20 in this example:

$"{value, -20}"

Is there a way to make an interpolated string like this:

$"{value, alignment}"

where alignment is a variable?

Wantage

string interpolation is just dressed up/hidden String.Format. If you can't do something via Format, you cannot do it via string interpolation. – Apiary

Answer 1

Unfortunately, alignment cannot be a variable. The alignment has to be a constant expression. Here is the relevant section from the docs

alignment: The constant expression whose value defines the minimum number of characters in the string representation of the result of the interpolated expression. If positive, the string representation is right-aligned; if negative, it's left-aligned. For more information, see Alignment Component.

Anglofrench

This seems weird. If result string can be composed from dynamic variables, why they need constant expression for alignment? The output need to be evaluated at runtime anyway, right? – Headstock

Answer 2

As previously mentioned alignment must be constant, but could try using Padleft in a similar fashion (not sure if that would work for you or not).

That or would have to have various string interpolations for 1 string.

string test;

if (value.length > 100)
     test = "${value: -20}";
else test = "${value : 20}";

Hope this helps.

Pyosis

Answer 3

Why not pad left?

    var p = Math.Max(Math.Max(a.Length, b.Length), c.Length);

    Console.WriteLine(a.PadLeft(p));
    Console.WriteLine(b.PadLeft(p) + " +");
    Console.WriteLine(new string('-', p));
    Console.WriteLine(c.PadLeft(p));

It's dynamic and (in my use case) adaptive:

Mimi