ROOT_NAME get root name

ROOT_NAME(P) returns the root name of P. root_name is the drive letter on Windows without the trailing slash or an empty string if P is not an absolute path. on non-Windows platforms, root_name is always an empty string.

function r = root_name(p)
arguments
  p string
end

r = repmat("", size(p));

if ispc()
  i = startsWith(p, lettersPattern(1) + ":");
  r(i) = extractBefore(p(i), 3);
end

end