Compilare: main.cpp: In function 'Num eval()': main.cpp:50:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (p < str.size () && (str[p] == '/' || str[p] == '*')) { ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:64:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("expresie3.in", "r", stdin); ^ main.cpp:65:43: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("expresie3.out", "w", stdout); ^