function oldpath = addpath(varargin)

%ADDPATH Add folder to search path.

%   ADDPATH FOLDERNAME prepends the specified folder to the current

%   matlabpath.  Surround FOLDERNAME in quotes if the name contains a

%   space.  If FOLDERNAME is a set of multiple folders separated by path

%   separators, then each of the specified folders will be added.

%

%   ADDPATH FOLDERNAME1 FOLDERNAME2 FOLDERNAME3 ...  prepends all the 

%   specified folders to the path.

%

%   ADDPATH ... -END    appends the specified folders.

%   ADDPATH ... -BEGIN  prepends the specified folders.

%   ADDPATH ... -FROZEN disables folder change detection for folders

%                       being added.

%

%   Use the functional form of ADDPATH, such as 

%   ADDPATH('folder1','folder2',...), when the folder specification is 

%   a variable or string.

%

%   P = ADDPATH(...) returns the path prior to adding the specified paths.

%

%   Examples

%       addpath c:\matlab\work

%       addpath /home/user/matlab

%       addpath /home/user/matlab:/home/user/matlab/test:

%       addpath /home/user/matlab /home/user/matlab/test

%

%   See also RMPATH, PATHTOOL, PATH, SAVEPATH, USERPATH, GENPATH, REHASH.

%   Copyright 1984-2017 The MathWorks, Inc.

% Number of  input arguments

n = nargin; 

narginchk(1,Inf); 

[varargin{:}] = convertStringsToChars(varargin{:}); 

if nargout>0 

    oldpath = path;

end 

append = -1; 

freeze = 0; 

args = varargin; 

while (n > 1)    

    last = args{n}; 

    % Append or prepend to the existing path

    if isequal(last,1) || strcmpi(last,'-end') 

        if (append < 0), append = 1; end; 

        n = n - 1;

    elseif isequal(last,0) || strcmpi(last,'-begin') 

        if (append < 0), append = 0; end;

        n = n - 1;

    elseif strcmpi(last,'-frozen')  

        freeze = 1;

        n = n - 1;

    else 

        break; 

    end

end

if (append < 0), append = 0; end 

% Check, trim, and concatenate the input strings

p = catdirs(mfilename, varargin{1:n}); 

% If p is empty then return

if isempty(p) 

    return;

elseif ~isempty(strfind(p, char(0))) 

    error(message('MATLAB:FileManip:NullCharacterInName'));

end 

% See whether frozen is desired, where the state is not already set frozen

if freeze 

    paths = strsplit(p,pathsep());

    for n = 1:size(paths,2)-1

        feature('DirectoryFreeze',paths{n});

    end

end 

% Append or prepend the new path

mp = matlabpath; 

if append 

    path(mp, p);

else 

    path(p, mp); 

end