performance: fullfile function execution efficiency could be improved.

The fullfile execution efficiency could be improved with the following tests：

t1 = tic;
for i = 1:10000
    f = fullfile('c:\','myfiles','matlab',filesep);
end
elapsedTime1 = toc(t1)

elapsedTime1 = 0.3777

t2 = tic;
for i = 1:10000
    f = "c:/"+"myfiles/"+"matlab"+filesep;
end
elapsedTime2 = toc(t2)

elapsedTime2 = 0.0163

elapsedTime1/elapsedTime2

ans = 23.1725

Answer 1

[Jan]

Seriously?

fullfile inserts file separators on demand, while your code is a simple concatenation of strings. In addition fullfile considers CHAR vectors, strings. cell strings and string arrays also. In your example you have to insert a file separator manually:

f = "c:/"+"myfiles/"+"matlab"+filesep;
%                 ^

But, yes, it can be improved. See FEX: JoinPath

t1 = tic;
for i = 1:10000
    f = fullfile('c:\','myfiles');
end
elapsedTime1 = toc(t1)

elapsedTime1 = 0.1240

t2 = tic;
for i = 1:10000
    f = JoinPath('c:\','myfiles');
end
elapsedTime2 = toc(t2)

elapsedTime2 = 0.0723

function F = JoinPath(Arg1, Arg2, varargin)
% Join parts of path and file name
% FullName = JoinPath(string1, string2, ...)
% The input strings are joined to a file path. Leading and/or trailing file
% separators are considered. This works exactly as FULLFILE, but is is
% faster.
%
% See also FULLFILE, FILEPARTS, SplitFile, TrailFSep, GetFileName, ParentPath.
%
% Tested: Matlab 6.5, 7.7, 7.8, 7.13, 8.6, WinXP/32, Win7/64
% Author: Jan Simon, Heidelberg, (C) 2009-2016 matlab.2010(a)n(MINUS)simon.de
% $JRev: R-k V:028 Sum:cbAk1P0AGf1V Date:18-Feb-2016 23:42:43 $
% $License: BSD (use/copy/change/redistribute on own risk, mention the author) $
% $UnitTest: uTest_JoinPath $
% $File: Tools\GLFile\JoinPath.m $
% History:
% 028: 18-Feb-2016 23:37, Published in FileExchange.
%      Replace file separators from \ to / or vice versa.

% Get file separators:
persistent FSep wuFSep
if isempty(FSep)
  FSep = filesep;
  if FSep == '\'
    wuFSep = '/';
  else
    wuFSep = '\';
  end
end
% Join the parts:
nArg = nargin;
if nArg >= 2
   Arg1 = strrep(Arg1, wuFSep, FSep);
   Arg2 = strrep(Arg2, wuFSep, FSep);
   lArg1 = length(Arg1);      % Optimized for most frequent task - 2 arguments:
   lArg2 = length(Arg2);
   if lArg1 * lArg2 ~= 0      % faster than: ~isempty(Arg1) && ~isempty(Arg2)
      if Arg1(lArg1) ~= FSep
         if Arg2(1) ~= FSep
            F = [Arg1, FSep, Arg2];
         else                 % Arg2 starts with separator
            F = [Arg1, Arg2];
         end
      else                    % Arg1 end with separator
         if Arg2(1) ~= FSep
            F = [Arg1, Arg2];
         else                 % Arg2 starts with separator
            Arg1(lArg1) = [];
            F = [Arg1, Arg2];
         end
      end
   else
      F = [Arg1, Arg2];
   end
   
   % Append arguments from 3 to end:
   if nArg > 2
      ArgC = strrep(varargin, wuFSep, FSep);
      for iC = 1:length(varargin)
         P  = ArgC{iC};
         lF = length(F);
         lP = length(P);
         if lF * lP ~= 0            % same as: ~isempty(F) & ~isempty(P)
            if F(lF) ~= FSep
               if P(1) ~= FSep
                  F = [F, FSep, P]; %#ok<AGROW>
               else                 % P starts with separator
                  F = [F, P];       %#ok<AGROW>
               end
            else                    % F ends with separator
               if P(1) == FSep      % Consider leading separator of P:
                  F(lF) = [];
               end
               F = [F, P];          %#ok<AGROW>
            end
         else                       % Either F or P is empty:
            F = [F, P];             %#ok<AGROW>
         end
      end  % for i
   end  % if nArg > 2
   
elseif nArg == 1
   F = strrep(Arg1, wuFSep, FSep);
   
elseif nArg == 0
   F = '';
end
end

[cui,xingxing]

your are right ,thank you for your privide FEX example.