Scan through a txt-file and find certain strings and replace certain lines by replacing strings

Hi, It's been a while since I've used Matlab and I just couldn't figure out how to make this work.

I am trying to edit a dxf-file (saved in .txt of course) and it is very important not to modify the structure of the code - at all! I want to scan the file line-by-line and find the lines which match the string str1='E_FROM'. After the scanning I should change spesific lines near the line which matches the string str1. I think it is wisest to first scan through the document and store the lines I am searching for. Now that I know where those lines are I want to modify the document. In my case I want to erase the string 14 lines above the "E_FROM" line. How this should be done. Please, help!

-Kalle

[KSSV]

Attaching file..will give you exact code....

[Kalle Palola]

Thanks for the extremely fast reply. However I couldn't find any files attached.

Answer 1

[Are Mjaavatten]

fid = fopen('in.txt');
lines = textscan(fid,'%s','delimiter','\n');
fclose(fid);  
lines = lines{1};
relevant =  find(~cellfun(@isempty,strfind(s{1},'E_FROM')));
for i = 1:length(relevant)
    lines{relevant(i)-14} = <modified line>;
end
fid = fopen('out.txt','w');
for i = 1:length(lines)
    fprintf(fid,'%s\n',lines{i});
end
fclose(fid)