Compilare: user.c: In function ‘main’: user.c:38:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.in","r",stdin),freopen("trie.out","w",stdout); ^ user.c:38:38: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.in","r",stdin),freopen("trie.out","w",stdout); ^ user.c:40:46: warning: ignoring return value of ‘gets’, declared with attribute warn_unused_result [-Wunused-result] s->c=s->n=0,memset(s->f,0,sizeof(s->f)),gets(l); ^ user.c:50:13: warning: ignoring return value of ‘gets’, declared with attribute warn_unused_result [-Wunused-result] gets(l); ^ /tmp/ccvQAZdL.o: In function `main': user.c:(.text.startup+0x7f): warning: the `gets' function is dangerous and should not be used.