foo.cc: In function 'void change_lowercase(std::string&)':
foo.cc:10:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |  for(int i = 0; i < s.size(); i++)
      |                 ~~^~~~~~~~~~
foo.cc: In function 'void cutpair(std::string, std::vector<codepair>&)':
foo.cc:30:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |  while(s[i] == ' ' && i < s.size()) cout << ' ', ++i;
      |                       ~~^~~~~~~~~~
foo.cc:31:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |  while(i < s.size()) {
      |        ~~^~~~~~~~~~
foo.cc:34:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |   while(++i, i < s.size() && s[i] == ' ') ++t.spmid;
      |              ~~^~~~~~~~~~
foo.cc:35:8: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |   if(i == s.size()) {
      |      ~~^~~~~~~~~~~
foo.cc:41:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |   while(++i, i < s.size() && s[i] == ' ') ++t.spnext;
      |              ~~^~~~~~~~~~
foo.cc: In function 'void putdecode(codepair)':
foo.cc:66:31: warning: array subscript has type 'char' [-Wchar-subscripts]
   66 |  pair<int, int> a = mapcode[p.f];
      |                             ~~^
foo.cc:67:31: warning: array subscript has type 'char' [-Wchar-subscripts]
   67 |  pair<int, int> b = mapcode[p.r];
      |                             ~~^
foo.cc: In function 'int main()':
foo.cc:101:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |  for(int i = 0; i < k.size(); i++) {
      |                 ~~^~~~~~~~~~
foo.cc:103:19: warning: array subscript has type 'char' [-Wchar-subscripts]
  103 |   else if(uni[k[i]]) continue;
      |                   ^
foo.cc:106:12: warning: array subscript has type 'char' [-Wchar-subscripts]
  106 |    uni[k[i]] = true, mapcode[k[i]] = make_pair(p, q);
      |            ^
foo.cc:106:34: warning: array subscript has type 'char' [-Wchar-subscripts]
  106 |    uni[k[i]] = true, mapcode[k[i]] = make_pair(p, q);
      |                                  ^
foo.cc:138:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<codepair>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  138 |  for(int i = 0; i < v.size(); i++) {
      |                 ~~^~~~~~~~~~

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