Compilare: user.cpp: In function ‘Trie* upd(Trie*, char*, int)’: user.cpp:36:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:89:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.in","r",stdin); ^ user.cpp:90:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.out","w",stdout); ^ user.cpp:92:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(A); ^ user.cpp:93:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ user.cpp:96:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccfzK3ed.o: In function `main': user.cpp:(.text.startup+0x85): warning: the `gets' function is dangerous and should not be used.