Interpolation string from variable c#

Question

I'm trying to interpolate a string combined of two strings in C#. I have following code in VS 2015:

DateTime date = DateTime.Now;
string username = "abc";
string mask = "{date:yy}/{username}";

What I want in result is:

18/abc

I know that I can interpolate it like:

mask = $"{date:yy}/{username}"

but mask is also an input. So i need something like:

string result = $"{mask}"

but the result is :

"{date:yy}/{username}"

Mask is actually downloaded from the database and in each case sequence of information can be different. I need to store in db whole mask and only complement it in code. I can't use String.Replace() method like

mask.Replace({date}, date.ToString())

because I need to have possibility to add some formatting like :yy, :yyyy, :dd etc.

Is there any possibility to do this?

Answer 1

Sure string.Format()

string mask = string.Format("{0:yy}/{1}", date, username);

or string interpolation

string mask = $"{date:yy}/{username}";

Answer 2

You can use string.Format() for that:

string mask = GetMaskFromDB(); //assume it returns "{0}/{1:yy}"
string username = "abc";
DateTime dt = DateTime.Now;

var result = string.Format(mask, username, dt);

Result: "abc/18"

References: DotNetFiddle Example , String.Format Method