Compilare: user.cpp: In function ‘int main()’: user.cpp:54:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < s.length(); ) { ~~^~~~~~~~~~~~ user.cpp:68:57: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!operators.empty() && priority[operators.back()] >= priority[s[i]]) pop(); ^ user.cpp:68:75: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!operators.empty() && priority[operators.back()] >= priority[s[i]]) pop(); ^ user.cpp:40:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.in", "r", stdin); ^ user.cpp:41:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.out", "w", stdout); ^