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

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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');
% 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');
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 ?

Accepted Answer

Thorsten on 14 Oct 2015
Edited: Thorsten on 14 Oct 2015
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');
fid = fopen(filename,'w');

More Answers (1)

Stephen23 on 14 Oct 2015
Edited: Stephen23 on 14 Oct 2015
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');
fid = fopen('new.txt','w');
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
Stephen23 on 16 Oct 2015
"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.

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