time   calls  line
                  1 function f = fullfile(varargin)
                  2 %FULLFILE Build full filename from parts.
                  3 %   FULLFILE(D1,D2, ... ,FILE) builds a full file name from the
                  4 %   directories D1,D2, etc and filename FILE specified.  This is
                  5 %   conceptually equivalent to
                  6 %
                  7 %      F = [D1 filesep D2 filesep ... filesep FILE] 
                  8 %
                  9 %   except that care is taken to handle the cases where the directory
                 10 %   parts D1, D2, etc. may begin or end in a filesep. Specify FILE = ''
                 11 %   to build a pathname from parts. 
                 12 %
                 13 %   Examples
                 14 %     To build platform dependent paths to files:
                 15 %        fullfile(matlabroot,'toolbox','matlab','general','Contents.m')
                 16 %
                 17 %     To build platform dependent paths to a directory:
                 18 %        addpath(fullfile(matlabroot,'toolbox','matlab',''))
                 19 %
                 20 %   See also FILESEP, PATHSEP, FILEPARTS.
                 21 
                 22 %   Copyright 1984-2005 The MathWorks, Inc.
                 23 %   $Revision: 1.19.4.4 $ $Date: 2009/02/13 15:12:17 $
                 24 
  0.01      40   25 error(nargchk(1, Inf, nargin, 'struct')); 
                 26 
            40   27 fs = filesep;  
            40   28 f = varargin{1}; 
            40   29 bIsPC = ispc; 
                 30 
            40   31 for i=2:nargin, 
            40   32    part = varargin{i}; 
            40   33    if isempty(f) || isempty(part) 
                 34       f = [f part]; %#ok<AGROW>
            40   35    else 
                 36       % Handle the three possible cases
            40   37       if (f(end)==fs) && (part(1)==fs), 
                 38          f = [f part(2:end)]; %#ok<AGROW>
            40   39       elseif (f(end)==fs) || (part(1)==fs || (bIsPC && (f(end)=='/' || part(1)=='/')) ) 
                 40          f = [f part]; %#ok<AGROW>
            40   41       else 
            40   42          f = [f fs part]; %#ok<AGROW> 
            40   43       end 
            40   44    end 
            40   45 end 
                 46 
                 47 % Be robust to / or \ on PC
            40   48 if bIsPC 
                 49    f = strrep(f,'/','\');
                 50 end

Other subfunctions in this file are not included in this listing.