how to add to txt file from certain point

Hi, I have a txt file which is a matrix [col1 col2 col3] (n rows) , i want to input a loop i=1:1:7 that will be added as a 4th col. [col1 col2 col3 1] [col1 col2 col3 2] [col1 col2 col3 3] so on until [col1 col2 col3 7] and then repeat itself until the n row, how can i do that?

Answer 1

[Cedric]

One way would be the following:

 fid_in  = fopen('inFile.txt', 'r') ;
 fid_out = fopen('outFile.txt', 'w') ;
 cnt = 0 ;
 while ~feof(fid_in)
    if cnt == 7,  cnt = 1 ;  else  cnt = cnt + 1 ;  end
    fprintf(fid_out, '%s %d\r\n', fgetl(fid_in), cnt) ;
 end
 fclose(fid_in) ;
 fclose(fid_out) ;

[Ilana]

Works! thanks!