Compilare: main.cpp: In function 'int main()': main.cpp:81:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 81 | for(int i=0;i<s.size();i++) | ~^~~~~~~~~ main.cpp:90:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 90 | while(i < s.size() && isalpha(s[i]) ) | ~~^~~~~~~~~~ main.cpp:137:13: warning: array subscript has type 'char' [-Wchar-subscripts] 137 | val[x]=!val[x]; | ^ main.cpp:137:21: warning: array subscript has type 'char' [-Wchar-subscripts] 137 | val[x]=!val[x]; | ^