getting automatically the initials of names

Question

This sounds like some basic stuff, and yet I cannot manage to find a solution, packaged or native.

I have documents with people who have from 2 to 4 names (typical Danish name could be Søren Jens Sørensen Hjortshøj).

Can someone suggest a command that would extract the initials (first letter) of each of those words ? I know of the package xstring to extract the first letter. The trouble is looping on the words, as I don't know the number in advance.

So the command \initials would act like this :

\NewDocumentCommand{\initials}{m} {
Some code
}
...
\ingenior{Søren Jens Sørensen Hjortshøj}
....
\initials{\ingenior} is SJSH.

Answer 1

This is a modified version of my answer at https://tex.stackexchange.com/a/705530/. The idea is to create a recursive function that prints the first character, splits the string on the first space, and calls itself on the rest if the rest is not empty.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{xstring}
\NewDocumentCommand{\initials}{m}{%
    \StrLeft{#1}{1}%           % print first character
    \StrBehind{#1}{ }[\rest]%  % copy everything after first space into \rest
    \IfStrEq{\rest}{}{}{%      % if rest is empty (first {}) do nothing (second {}),
                               % which will stop the recursive loop.
    \initials{\rest}%          % else: call the function again on the rest
    }%
}
\def\ingenior{Søren Jens Sørensen Hjortshøj}
\begin{document}
The initials of \ingenior\ are \initials{\ingenior}.
\end{document}

Result: