For the case where looking for a specific string:
varargin = {'aaa','bbb',13,{'a','b'},[12 34],'ccc'} % let's pretend we have some varargin
% test to see if a certain string is in varargin
vararginhas_bbb = strismember('bbb',varargin) % returns true
vararginhas_b = strismember('b',varargin) % returns false
where strismember() is the following function:
function yeah=strismember(thing,setofthings)
% YEAHITIS=STRISMEMBER(STRING,SETOFSTRINGS)
% Returns true if the character array STRING is a member of the
% cell array SETOFSTRINGS. This is generally faster than using
% ismember() -- about 2x as fast in recent versions, and up to
% 50x as fast in older versions. Numeric inputs are not supported.
%
% See also: ismember, strcmp
yeah=~isempty(find(strcmp(thing,setofthings),1));
If you wanted to see if varargin contained any arguments of a certain type:
vararginhas_cell = any(cellfun(@iscell,varargin)) % returns true
vararginhas_struct = any(cellfun(@isstruct,varargin)) % returns false
I'm sure there are better, more preferred ways
