The problem is:
~ischar(varargin(1:2:nargin))
The varargin input will always be a cell-array, so this condition will never be true.
I think what you want is:
~iscellstr(varargin(1:2:nargin))
This will verify that the input is a cell-array whose elements are all character vectors.
But, putting any issues in the code aside, unless I'm missing something, your entire function can be written like this:
function db = name_value_pairs(varargin)
if mod(nargin,2)~=0 || ~iscellstr(varargin(1:2:nargin))
db = {};
else
db = varargin;
end
In addition, unless you require the added validation, your function can be replaced in your code by just wrapping your inputs in curly braces.
db = name_value_pairs('a',10,'b',20);
db2 = {'a',10,'b',20};
% db and db2 will be the same
