Function generate the file names and directory names in a directory tree by walking the tree top-down. For each directory in the tree rooted at directory topPath. For each directory of tree you can call "Visitor Function" for files processing.

Using:
[pathNames, dirNames, fileNames] = dirwalk(topPath)
dirwalk(topPath, visitor)
[visitorOutput1, visitorOutput2, ..., visitorOutputN] = dirwalk(topPath, visitor)
[...] = dirwalk(topPath, visitor, visitorInput1, visitorInput2, ..., visitorInputN)

Example:
topPath = fullfile(matlabroot, 'toolbox', 'matlab', 'demos');

% Get files and dirs listing (default visitor)
[pathNames, dirNames, fileNames] = dirwalk(topPath);

% Call visitor function in each dir
dirwalk(topPath, @(y,x) disp(strcat(y, filesep, {x.name}')))

See help DIRWALK and TEST_DIRWALK for detailes examples.