How to insert file name into an array?

I have a sequence of 62496 files. Each file name has information about height, year, month, day, hour and minute, for example, 14000_20140615_03000.dat

My script looks like the following:

clear all;
close all;

str='../Documents/';
folder_name = uigetdir(str);
files = dir(fullfile(folder_name,'*.dat'));
curr_folder=pwd;
cd(folder_name);

for i = 1: length(files);
    
    fileID = fopen(files(i).name); 
    var = fread(fileID,[500 500], 'float32'); 
  
    var20 = find(var>=20);
    
end

I want to create a matrix with the index of var20 and the height of this data, which is the information in the file name. That is, I need to obtain a matrix with two columns like this:

18582 14000

19647 14000

15824 14000

...

Answer 1

[dpb]

str='../Documents/';
folder_name = uigetdir(str);
d=dir(fullfile(folder_name,'*.dat'));
for i = 1: length(files);
  fid=fopen(fullfile(d(i).folder,d(i).name); 
  var = fread(fileID,[500 500], 'float32'); 
  fid=fclose(fid);
  var20 = find(var>=20);
  ht=str2double(extractBefore(d(i).name,'_'));      % get the height number from filename
  heightArray=[repmat(ht,numel(var20),1) var20];    % create the new array
  % either use these data here or save to new file or whatever before going on to next...
  ...
end