Compilare: user.c: In function ‘main’: user.c:59:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:60:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:100:5: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result] write(1, obuf + oblen + 1, (CHUNK >> 2) - oblen - 2); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~