Compilare: user.cpp: In function ‘int GetIndexFor(int)’: user.cpp:42:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; step < v.size(); step <<= 1); ^ user.cpp:46:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i + step < v.size() && v[i + step] <= x) ^ user.cpp: In function ‘int main()’: user.cpp:15:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expr.in", "r", stdin); ^ user.cpp:17:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", expression); ^ user.cpp:19:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expr.in", "r", stdin); ^ user.cpp:20:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expr.out", "w", stdout); ^