Compilare: user.cpp: In function ‘void add_intrie(int)’: user.cpp:23:20: warning: variable ‘x’ set but not used [-Wunused-but-set-variable] int i=startpos,x,y,j; trie *a=root; ^ user.cpp: In function ‘int main()’: user.cpp:41:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix2.in","r",stdin); ^ user.cpp:42:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix2.out","w",stdout); ^ user.cpp:43:10: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); n=strlen(s+1); root=new trie; ^ /tmp/ccWEH4Jj.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.