Loop to open files / extract image data and save them in a matrix

I have an image database as files (106 files and each file contains 48 images)

I want to generate a matrix for the database (db.mat)

I want my program to open each folder (from 001 to 106) and take the data and save it to a db.mat file

here is my prog :

clear all;
clc;
cd D:\001\FT-2BU\FT-2BU
s = '';
str1 ='00';
str2 ='0';
for i=1:106
	if i<10 
	s=strcat(str1,i);
    bmpFiles = dir('*.bmp'); 
    numfiles = length(bmpFiles);
    mydata = cell(1, numfiles);
    for k = 1:numfiles 
    mydata{k} = imread(bmpFiles(k).name);
    end
    save mydata;
    elseif i<100
	s=strcat(str2,i);
    bmpFiles = dir('*.bmp');
    numfiles = length(bmpFiles);
    mydata = cell(1, numfiles);
    for k = 1:numfiles 
    mydata{k} = imread(bmpFiles(k).name); 
    end
    save mydata;
    
    else
    s=i;
    bmpFiles = dir('*.bmp');
    numfiles = length(bmpFiles);
    mydata = cell(1, numfiles);
    for k = 1:numfiles 
    mydata{k} = imread(bmpFiles(k).name); 
    end
    save mydata; end
end
end

Answer 1

[michael scheinfeild]

you need take subfolder , create it use num2str(number)

dir(fullfile(folder,subfolder))

[Harizi Amira]

Can you explain to me why this error appears, despite the fact that the file 1_1.bmp exists in bmpFiles structure !

Answer 2

[michael scheinfeild]

look your bmp files empty

[Harizi Amira]

the BMP file is empty because I can not open the files one by one

here is the little program for a single file what gave me, it works correctly.

now I want to generate the matrix for all files