Compilare: main.cpp: In function 'int num(std::string)': main.cpp:43:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 43 | for(int i = 0; i < a.size(); i++) | ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:60:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 60 | for(int i = 0; i < s.size(); i++) | ~~^~~~~~~~~~ main.cpp:64:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 64 | while(i < s.size() && isdigit(s[i])) | ~~^~~~~~~~~~