How to add rows to string array using a loop

I would appreciate help on how to add data to subsequent rows of an array.

I am reading PDF file and extracting the data and simply trying to add each row of data a string array for each iteration of the loop but I have not been been able to understand how to do this

files = dir(fullfile(PDFfolder, '*.pdf'))
L = length(files)
DataCompiled = strings(L,5) %Preallocated with 5 rows

for i = 1:L
    file = files(i).name;   
    
    [filepath,IDnum,ext] = fileparts(file);
    
    %Text Extracted from PDF files
    str = extractFileText(file);
    NameEmail = extractBetween(str, 'From:', 'To');
    Email = extractBetween(NameEmail, '<','>');
    FirstName = extractBefore(Email, '.');
    LastName = extractBetween(Email,'.','@');
    
    prefix = 'ABC-';
    SubjectID = [prefix,IDnum];
    
    Data = [SubjectID FirstName LastName Email]
    
    for 
    %How to iterate and build an array with subsequent rows filled in with
    %each loop
    end
end      

Answer 1

[Voss]

Try something like this:

files = dir(fullfile(PDFfolder, '*.pdf'));
L = length(files);
DataCompiled = strings(L,4); %Preallocated with *4* *columns* (SubjectID, FirstName, LastName, Email)

% construct full-path file names:
file_names = fullfile({files.folder},{files.name});

for i = 1:L
    
    % "filepath" is apparently unused, so you can replace it with "~" here,
    % and "ext" is apparently unused, so you can remove it here
    [~,IDnum] = fileparts(file_names{ii});
    
    %Text Extracted from PDF files
    str = extractFileText(file_names{ii});
    NameEmail = extractBetween(str, 'From:', 'To');
    Email = extractBetween(NameEmail, '<','>');
    FirstName = extractBefore(Email, '.');
    LastName = extractBetween(Email,'.','@');
    
    % use string concatenation (+)
    SubjectID = "ABC-" + IDnum;
    % (but concatenation of character vectors would also work because SubjectID
    % will be assigned into the string array "DataCompiled")
%     SubjectID = ['ABC-',IDnum];
    
    % put the strings in the i-th row of DataCompiled
    DataCompiled(i,:) = [SubjectID FirstName LastName Email];
    
end