Textscan skips desired white space at begin of line - matlab

Question

To run a certain software I'm using .txt-input files which I need to manipulate with Matlab.
I know how to do it, and I didn't expected problems. As it was not working I reduced my manipulation script to a minimum, so actually nothing is changed. Except some white spaces, and the other software seems to react very sensitive on that.
parts of my file look like that:
...
*CONTROL_TERMINATION
$# endtim endcyc dtmin endeng endmas
1.000000 0 0.000 0.000 0.000
*CONTROL_TIMESTEP
$# dtinit tssfac isdo tslimt dt2ms lctm erode ms1st
0.000 0.900000 0 0.000 -1.000E-4 0 0 0
$# dt2msf dt2mslc imscl
0.000 0 0
...
I'm loading it to Matlab and directly save it again without changes:
% read original file
fid = fopen('filename.txt','r');
param = textscan(fid,'%s','delimiter','\n');
rows = param{1,1};
fclose(fid);
% overwrite to new file
fid = fopen('filename.txt','w');
fprintf(fid, '%s\r\n', rows{:});
fclose(fid);
The output file is lacking of the white spaces at the begin of every line, that seems to be the only difference of input and output file. (at least I hope so)
...
*CONTROL_TERMINATION
$# endtim endcyc dtmin endeng endmas
1.000000 0 0.000 0.000 0.000
*CONTROL_TIMESTEP
$# dtinit tssfac isdo tslimt dt2ms lctm erode ms1st
0.000 0.900000 0 0.000 -1.000E-4 0 0 0
$# dt2msf dt2mslc imscl
0.000 0 0
...
Though it seems weird to me, that this should be the reason - what can I change, that both files look 100% identical? The problem I'm having is that the white spaces have different lengths.

Answer 1

You can use the whitespace option in textscan, and setting it to an empty string.
param = textscan(fid,'%s','delimiter','\n','whitespace','');
By default, textscan does not include leading white-space characters in the processing of any data fields (doc center).