Compilare: user.cpp: In function ‘int main()’: user.cpp:9:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.in","r",stdin); ^ user.cpp:10:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.out","w",stdout); ^ user.cpp:11:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ user.cpp:14:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccRelA0b.o: In function `main': user.cpp:(.text.startup+0x85): warning: the `gets' function is dangerous and should not be used.