Compilare: main.cpp: In function 'int main()': main.cpp:14:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 14 | for(int i=0;i<s2.size();i++) | ~^~~~~~~~~~ main.cpp:16:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 16 | for(int i=0;i<s1.size();i++) | ~^~~~~~~~~~ main.cpp:19:19: warning: array subscript has type 'char' [-Wchar-subscripts] 19 | r2[cnr++]=s1[i]; | ~~~^~