How to read multi .txt files and extract files which are started with the specific name and write all these files in a new .txt file?

I have around 10000 .dat files. Their names are like this :

tag-klima-500-1987-1_12.dat ; tag-klima-500-1987-1_12.dat ; tag-klima-905-1987-1_12.dat ; tag-klima-905-1987-1_12.dat

I need to read those files with the same middle number, for example, all those that have 500 , or 905 in the middle. And then write all data belong to each group (groups which have identification of 500 or 905) in a .txt file.

I could read and write for files belong to each group, for example for files starting with tag-klima-905, but I have stuck to do it for all file at the same time when running the codes.

pth = 'E:\DATA\Agro\ZAMG\klima-ehsan-1987_2017'; 

fileList = dir(fullfile(pth, 'tag-klima-905*.dat'));

out      = fopen(fullfile(pth, 's905.txt'), 'w');
delimiter = '\t';
startRow = 2;
formatSpec = '%s%s%s%s%s%s%s%[^\n\r]';
for k = 1:numel(fileList)

 s = fileread(fullfile(pth, fileList(k).name));
  fwrite(out, s, 'char');
end

 fclose(out);

I appreciate any helps,

[Bob Thompson]

You could work this a couple of different ways. I would suggest some form of sorting using regexp().

https://www.mathworks.com/help/matlab/ref/regexp.html