Compilare: user.cpp: In function ‘int main()’: user.cpp:11:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<s.size();++i) ^ user.cpp:8:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("palindrom.in","r",stdin); ^ user.cpp:9:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("palindrom.out","w",stdout); ^