foo.cc: In function 'int main()':
foo.cc:8:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::array<char, 13>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |  for (int i = 0; i < arr.max_size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~~
foo.cc:12:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::array<char, 13>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |  for (int i = 0, j = 1; i < arr.max_size() - 1; i++) {
      |                         ~~^~~~~~~~~~~~~~~~~~~~
foo.cc:27:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::array<char, 13>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |   for (int i = 0; i < arr.max_size()-1; i++) {
      |                   ~~^~~~~~~~~~~~~~~~~~

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