Compilare: main.cpp: In function 'int main()': main.cpp:48:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 48 | for (int i = 0; i < expr.size(); ++i) { | ~~^~~~~~~~~~~~~ main.cpp:51:34: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 51 | while (i < expr.size() and isDigit(expr[i])) { | ~~^~~~~~~~~~~~~ main.cpp: In function 'int solve(int, int, char)': main.cpp:43:1: warning: control reaches end of non-void function [-Wreturn-type] 43 | } | ^