what does . and .. refer to

    
        for i = 1:size(TrainFiles,1)
            if not(strcmp(TrainFiles(i).name,'.')|strcmp(TrainFiles(i).name,'..')|strcmp(TrainFiles(i).name,'Thumbs.db'))
                Train_Number = Train_Number + 1; % Number of all images in the training database
                name{Train_Number}=TrainFiles(i).name;
            end
        

[Walter Roberson]

User completely changed the question. However, the revised question is valid in itself.

Answer 1

[Image Analyst]

It's checking to make sure that the file is not the current folder (dot) or a link to the parent folder (dot dot).

[Image Analyst]

Actually, since it's just building up a cell array of image files, you'd be better off doing this:

% Get a list of all PNG image files in the specified folder.
filePattern = fullfile(yourImageFolder, '*.png')    % Or whatever your image extension is
fileStructure = dir(filePattern)    % Get info from all PNG files into a strcuture array.
% Now extract all the names from the file structure fields into a single cell array:
allFileNames = {fileStructure.name}

[Walter Roberson]

I would use

allFileNames = fullfile(yourImageFolder, {fileStructure.name});

[Image Analyst]

Yes. Or you could even use imDatastore().

Answer 2

[Steven Lord]

For the operating systems on which MATLAB is supported, . refers to the current directory and .. the parent directory, as stated on this Wikipedia page.