Compilare: main.cpp: In function 'void sum(std::string&, std::string)': main.cpp:13:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 13 | if(i>=a.size())a=a+'0'; | ~^~~~~~~~~~ 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 | else if(i>=b.size())b=b+'0'; | ~^~~~~~~~~~