1

Pass

!cp diff_digits.m safe
!rm *.*
!mv safe diff_digits.m
% Clean user's function from some known jailbreaking mechanisms
fid = fopen('diff_digits.m');
st = regexprep(char(fread(fid)'), '!', 'error(''No shell commands!''); %');
st = regexprep(st, 'feval', 'error(''No fancy functions!''); %');
st = regexprep(st, 'str2func', 'error(''No fancy functions!''); %');
st = regexprep(st, 'regex', 'error(''No fancy functions!''); %');
st = regexprep(st, 'system', 'error(''No shell commands!''); %');
st = regexprep(st, 'dos', 'error(''No shell commands!''); %');
st = regexprep(st, 'unix', 'error(''No shell commands!''); %');
st = regexprep(st, 'perl', 'error(''No external languages commands!''); %');
st = regexprep(st, 'java', 'error(''No external languages commands!''); %');
st = regexprep(st, 'assert', 'error(''No overwriting!''); %');
fclose(fid)
fid = fopen('diff_digits.m' , 'w');
fwrite(fid,st);
fclose(fid)
ans =
0
ans =
0

3

Pass

%%
start=1000; finish=9999; y_correct = 4536;
assert(isequal(diff_digits(start,finish),y_correct))
counter =
0
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1
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541
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581
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584
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587
cou...
