Compilare: user.cpp: In function ‘int main()’: user.cpp:75:42: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!op.empty() && pr[op.back()] >= pr[expr[cnt]]) { ^ user.cpp:75:59: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!op.empty() && pr[op.back()] >= pr[expr[cnt]]) { ^ user.cpp:46:39: 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:47:41: 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); ^ user.cpp:49:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s\n", expr); ^