Compilare: main.cpp: In function 'void doSet(std::__cxx11::string&)': main.cpp:25:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < s.size() && isdigit(s[i])) { ~~^~~~~~~~~~ main.cpp:30:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < s.size() && isdigit(s[i])) { ~~^~~~~~~~~~ main.cpp:35:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < s.size() && isdigit(s[i])) { ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:77:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) ~~^~~~~~~~~~ main.cpp:109:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < expr.size(); i++) ~~^~~~~~~~~~~~~