regexprep replacing two or more variables in a string of text (once) with ',' between them

hi a have bellow code for change an string in my text file

      fid = fopen('test.txt','r')

line = 0;

all ={};
while line ~= -1 
    line = fgets(fid);
    if line ~= -1
        all = [all;line];
        end

end
 fclose(fid) ;
buffer = fileread('test.txt') ;
i=4
     data = (all{i})

      c=300
      d= 200
           b = 'c , d'

   buffer = regexprep(buffer, data,b) ;
   fid = fopen('test.txt', 'w') ;
   fwrite(fid, buffer) ;
   fclose(fid) ;

i want to write c and d both with a ',' between them data (specific line) , but it (regexprep) not accept both of them with that format or i cant use it truly if anyone know how to fix that help! thanks

[Jan]

Please format your code using the "{} Code" button. Currently it is not readable.

You start with a lot code lines to import the file, only to import it again by a single line of code using fileread?

Answer 1

[Jan]

What is the purpose of the regexprep call? Is all you want to do to replace the 4.th line of the file by "300 , 200"? Then:

Data    = strsplit(fileread('test.txt'), char(10));   % Or TEXTSCAN
Data{4} = sprintf('%g, %g', 300, 200);
fid     = fopen('test.txt', 'w');
if fid == -1, error('Cannot open file for writing'); end
fprinft(fid, '%s\n', Data{:});
fclose(fid);

[mahdi salehzade]

yes its my purpose but i want do it buy two value of a function that change every time (get a and b from function and replace them in 4th line). and also your code clear other string of my file , i need to change just 4th line .

[Jan]

The shown code replaced the 4th line only. Why do you think that other strings are changed also?

If you want to insert two variables, modify the 2nd line:

Data{4} = sprintf('%g, %g', a, b);

Answer 2

[Walter Roberson]

Change

b = 'c , d'

to

b = sprintf('%g , %g', c, d)