Compilare: user.cpp: In function ‘std::vector<int> join(std::vector<int>&, std::vector<int>&)’: user.cpp:50:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ((i < left.size()) && (j < right.size())) { ^ user.cpp:50:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ((i < left.size()) && (j < right.size())) { ^ user.cpp:59:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < left.size()) { ^ user.cpp:63:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < right.size()) { ^ user.cpp: In function ‘int main()’: user.cpp:166:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.out", "w", stdout); ^ user.cpp: In member function ‘char hpstream::nextch()’: user.cpp:126:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(str, 1, BMAX, file); ^