Compilare: main.cpp: In function 'void skip_space()': main.cpp:23:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 23 | if (i < s.length() && s[i] == ' ') ++i; | ~~^~~~~~~~~~~~ main.cpp: In function 'bool OR()': main.cpp:28:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 28 | while (i + 1 < s.length() && s[i] == 'O' && s[i + 1] == 'R') { | ~~~~~~^~~~~~~~~~~~ main.cpp: In function 'bool AND()': main.cpp:39:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 39 | while (i + 2 < s.length() && s[i] == 'A' && s[i + 1] == 'N' && s[i + 2] == 'D') { | ~~~~~~^~~~~~~~~~~~ main.cpp:42:14: warning: unused variable 'next_value' [-Wunused-variable] 42 | bool next_value = TERM(); | ^~~~~~~~~~ main.cpp: In function 'bool TERM()': main.cpp:50:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 50 | if (i + 2 < s.length() && s[i] == 'N' && s[i + 1] == 'O' && s[i + 2] == 'T') { | ~~~~~~^~~~~~~~~~~~ main.cpp:55:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 55 | } else if (i < s.length() && s[i] == '(') { | ~~^~~~~~~~~~~~ main.cpp:63:25: warning: array subscript has type 'char' [-Wchar-subscripts] 63 | value = val[s[i]]; | ^ main.cpp: In function 'int main()': main.cpp:77:13: warning: array subscript has type 'char' [-Wchar-subscripts] 77 | val[variable] = !val[variable]; | ^~~~~~~~ main.cpp:77:30: warning: array subscript has type 'char' [-Wchar-subscripts] 77 | val[variable] = !val[variable]; | ^~~~~~~~ main.cpp:80:33: warning: second operand of conditional expression has no effect [-Wunused-value] 80 | fout << OR() ? '1' : '0'; | ^ main.cpp:80:33: warning: third operand of conditional expression has no effect [-Wunused-value]