MATLAB: Editing/Changing a text file’s content based on input variable

regexpstrings

I have a txt file which has the following content in the middle of the text:
set TC_SYS_01       0
set TC_SYS_02       0
...
set TC_SYS_38       0
Now if input is 10,the first 10 lines value has to be set to 1. example:=
set TC_SYS_01       1
...
set TC_SYS_10       1
———————————– Updated Code——————————
% if input says 10
content = fileread('run.txt');
newcontent = regexprep(content, '(?<=set TC_SYS_\d*\s+)[01]','0');
% the above line is just to make sure all of them are 0,if any of them are 1;
fid = fopen('run.txt','w');
fwrite(fid,newcontent);
fclose(fid);
% now all lines are value is 0.
% Variable is 10,so first 10 to be set to 1
content = fileread('run.txt');
%%%%%%%%%%%%%%%%%

newcontent = regexprep(content, '(?<=set TC_SYS_[0]\d\s+)[01]','1');   %this line
%%%%%%%%%%%%%%%%%
fid = fopen('run.txt','w');
fwrite(fid,newcontent);
fclose(fid);
how to write the line with comment 'this line' so that i can directly write the variable into expression instead of hard coding as i have done in the above code ?
This question is in some ways related to my previous question: http://in.mathworks.com/matlabcentral/answers/248317-change-the-content-in-an-m-file-based-on-check-box-input-from-gui

Best Answer

The idea is that you run the regexpr N times using the 'once' parameter. And you don't need so save the file intermediately after you have converted all the numbers to 0.
function changeTC_SYS(filename, N)
% Sets <num> to 1 in the first N lines of format "set TC_SYS_10 <num>". 
content = fileread(filename);
content = regexprep(content, '(?<=set TC_SYS_\d*\s+)[01]','0');
% the above line is just to make sure all of them are 0,if any of them are 1;
for i = 1:N
  content = regexprep(content, '(?<=set TC_SYS_\d*\s+)0', '1', 'once');
end
fid = fopen(filename,'w');
fwrite(fid,content);
fclose(fid);
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