Editing/Changing a text file's content based on input variable

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

Answer 1

[Thorsten]

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);

Answer 2

[Stephen23]

Try this code:

N = 5; % <- how many line to change to '1'.
S = fileread('run.txt');
S = regexprep(S, '1\s*?$','0','lineanchors');
for k = 1:N
    S = regexprep(S, '0\s*?$','1','lineanchors','once');
end
fid = fopen('new.txt','w');
fwrite(fid,S);
fclose(fid);

Which creates a text file new.txt that looks like this:

set TC_SYS_01       1
set TC_SYS_02       1
set TC_SYS_03       1
set TC_SYS_04       1
set TC_SYS_05       1
set TC_SYS_06       0
set TC_SYS_07       0
set TC_SYS_08       0
set TC_SYS_09       0
set TC_SYS_10       0
... etc

[Thorsten]

This changes all lines ending with 1 to 0, and after that the first N lines that end with 0 to end with 1. This works only if there are no other lines than

set TC_SYS_01   <1 or 0>

in the file that end with 0 or 1.

[Luffy]

@ Thorsten: Yes the above code was changing 6 other similar lines which were above the set TC_SYS_01 line. After running the above code,we can set the lines which got changed back to 0.

[Stephen23]

"This works only if there are no other lines than.." which is exactly what was specified in the question. If there are other lines in the file then I am sure that the OP would know this and realize that this important information should be described in their question.