fopen fidr code working

can anyone pls explain the code below. Thanks in advance.

fid_de = fopen('temp_de.txt','wt');
count = 1;
j = 1;
%write DE section
while(count <= 2*(max_xy-1))
de(1,:)=['     110' numstr(j,' ') '       0       0   10000       0       0       000000001' numstr(count,'D')];
fprintf(fid_de,[de(1,:) '\n']);
count = count + 1;
de(2,:)=['     110       0       0       1       0                Line           0' numstr(count,'D')];
fprintf(fid_de,[de(2,:) '\n']);
count = count + 1;
j = j + 1;
end;
fclose(fid_de);

fidr = fopen('temp_de.txt','rt');
while 1
    tline = fgetl(fidr);
    if ~ischar(tline),   break,   end
    fprintf(fidw,tline(1:80));
    fprintf(fidw,'\n');
end
fclose(fidr);
id = 2*(max_xy-1);

Answer 1

[Hari]

Hi,

I understand that you're trying to understand the purpose and functionality of a MATLAB script that writes formatted lines to a text file (temp_de.txt) and then reads it back to write a subset of the content into another file. The script involves string formatting, file I/O, and iterative control flow.

I assume that the variable max_xy is a predefined scalar that controls how many DE section lines are written, and fidw is a valid file identifier opened for writing before the second loop starts.

In order to understand what this code is doing, you can follow the below breakdown:

Step 1: Open a new file for writing DE section

fid_de = fopen('temp_de.txt','wt');

This opens a file in text mode for writing (wt). It will be used to store the "DE section" lines.

Step 2: Initialize counters

count = 1;
j = 1;

These counters control the generation of DE lines. count likely tracks line numbers or identifiers, and j may index blocks or elements.Step 3: Loop to write formatted DE lines

while(count <= 2*(max_xy-1))

This loop generates 2*(max_xy - 1) lines. Each iteration writes two lines formatted into de(1,:) and de(2,:) using custom number-to-string formatting via numstr() (assumed user-defined or pseudocode for num2str() with formatting).

Each DE block looks like:

• Line 1: Starts with "110", includes j, and ends with a numeric code involving count.
• Line 2: Also starts with "110", labels it a "Line", includes the next count.

Each line is printed to file using fprintf.

Step 4: Close the file

    fclose(fid_de);

Step 5: Reopen the file for reading and process each line

    fidr = fopen('temp_de.txt','rt');
    while 1
        tline = fgetl(fidr);
        if ~ischar(tline), break, end
        fprintf(fidw, tline(1:80));
        fprintf(fidw, '\n');
    end
    fclose(fidr);

This reads each line from the temporary file and writes only the first 80 characters of each line into another file associated with fidw.

Step 6: Final count assignment

    id = 2*(max_xy - 1);

Stores the total number of lines written, likely for further use.Summary:

• The code generates a formatted "DE section" and writes it to a file.
• Each DE block consists of two structured lines.
• The file is then reprocessed to extract only the first 80 characters from each line, possibly due to formatting standards.

Note: The function numstr() is not a standard MATLAB function; it likely mimics num2str() with padding. You may need to verify its implementation.

Refer to:

• "fopen": https://www.mathworks.com/help/matlab/ref/fopen.html
• "fprintf": https://www.mathworks.com/help/matlab/ref/fprintf.html
• "fgetl": https://www.mathworks.com/help/matlab/ref/fgetl.html

Hope this helps!