Problem using fprintf, extra character printed each line

I have two data structures:

atomName <855*1 cell>
atomSASA <855*1 double>

which I am using in code to produce an output file:

%write out SASA values for individual atoms to file
results_file = fopen('output.txt','w');

fprintf(results_file,'SASA for Individual Atoms: \n');
i=1;
while i < (855)
    fprintf(results_file,'Atom %s %s: %.3f\n',i,cell2mat(atomName(i)),atomSASA(i));
    i = i + 1;
end

The file seems correct for the first 32 lines, but starting at line 33, there is an extra character after the word Atom. The character changes each line, eventually going through digits, capital letters A-Z, lower letters a-z etc. I would like to remove this extra character from each line:

Atom ! HG23: 6.286
Atom " N: 0.000
Atom # CA: 0.000
Atom $ C: 0.000
Atom % O: 0.000
Atom & CB: 0.000
Atom ' CG: 0.000
Atom ( CD1: 0.000
Atom ) CD2: 0.000
Atom * CE1: 0.000
Atom + CE2: 0.000
Atom , CZ: 0.000
Atom - OH: 0.000
Atom . H: 0.000
Atom / HA: 0.000
Atom 0 HB2: 0.000
Atom 1 HB3: 0.000
Atom 2 HD1: 0.000
Atom 3 HD2: 0.000
Atom 4 HE1: 0.000
Atom 5 HE2: 0.000
Atom 6 HH: 0.000
Atom 7 N: 0.000
Atom 8 CA: 0.000
Atom 9 C: 0.000
Atom : O: 0.000
Atom ; CB: 0.000
Atom < CG: 0.000
Atom = CD: 0.000
Atom > CE: 1.208
Atom ? NZ: 1.312
Atom @ H: 0.000
Atom A HA: 0.000
Atom B HB2: 0.000
Atom C HB3: 0.000
Atom D HG2: 0.000
Atom E HG3: 0.000
Atom F HD2: 0.000
Atom G HD3: 0.000
Atom H HE2: 0.000
Atom I HE3: 33.979
Atom J HZ1: 0.000
Atom K HZ2: 0.000
Atom L HZ3: 44.513
Atom M N: 0.000
Atom N CA: 0.000
Atom O C: 0.000
Atom P O: 0.000
Atom Q CB: 0.000
Atom R CG: 0.000
Atom S CD1: 0.000
Atom T CD2: 0.000
Atom U H: 0.000
Atom V HA: 0.000
Atom W HB2: 0.000
Atom X HB3: 0.000
Atom Y HG: 0.000
Atom Z HD11: 0.000
Atom [ HD12: 0.000
Atom \ HD13: 0.000
Atom ] HD21: 0.000
Atom ^ HD22: 0.000
Atom _ HD23: 0.000
Atom ` N: 0.000
Atom a CA: 0.000
Atom b C: 0.000
Atom c O: 0.000
Atom d CB: 0.000
Atom e CG1: 0.000
Atom f CG2: 0.000

Answer 1

[Image Analyst]

Try this:

results_file = 1; % Let's use the command window until we get it figured out.
fprintf(results_file,'SASA for Individual Atoms: \n');
for k = 1 : 855
    fprintf(results_file,'Atom %d %s: %.3f\n', k, atomName{k}, atomSASA(k));
end

Remember to get rid of the results_file = 1; line once you have it debugged!

Answer 2

[per isakson]

Hint:

    >> char( 33:80 )
    ans =
    !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOP

it's the counter, i, that causes the extra character

    >> sprintf('%s', 33:37 )
    ans =
    !"#$%