Is there a better way to create acronym from upper letters in C#?

Question

What is the best way to create acronym from upper letters in C#?

Example:

Alfa_BetaGameDelta_Epsilon

Expected r

Answer 1

var str = "Alfa_BetaGammaDelta_Epsilon";
var abbreviation = string.Join(string.Empty, str.Where(c => c.IsUpper()));