Textscan skips desired white space at begin of line

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).