Compilare: main.cpp: In function 'bool isVariable(char, int)': main.cpp:49:87: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 49 | return c >= 'A' && c <= 'Z' && (s[pos + 1] == ' ' || s[pos + 1] == ')' || pos + 1 == s.size()); | ~~~~~~~~^~~~~~~~~~~ main.cpp: In function 'std::string getOp(int)': main.cpp:54:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 54 | while (s[pos] != ' ' && pos < s.size()) { | ~~~~^~~~~~~~~~ main.cpp: In function 'bool eval()': main.cpp:63:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 63 | for (int i = 0; i < s.size(); i++) { | ~~^~~~~~~~~~ main.cpp:94:29: warning: array subscript has type 'char' [-Wchar-subscripts] 94 | values.push(val[c]); | ^ main.cpp: In function 'int main()': main.cpp:154:13: warning: array subscript has type 'char' [-Wchar-subscripts] 154 | val[it] = !val[it]; | ^~ main.cpp:154:24: warning: array subscript has type 'char' [-Wchar-subscripts] 154 | val[it] = !val[it]; | ^~ main.cpp:148:10: warning: unused variable 'garbage' [-Wunused-variable] 148 | char garbage; | ^~~~~~~