Compilare: user.cpp: In function ‘int main()’: user.cpp:166:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d ", &N, &K, &W, &D); ^ user.cpp:170:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S); ^ user.cpp: In function ‘void query(trie*, int)’: user.cpp:150:5: warning: ‘exista’ may be used uninitialized in this function [-Wmaybe-uninitialized] if( !exista ) ^ /tmp/ccJCdC64.o: In function `main': user.cpp:(.text.startup+0x58): warning: the `gets' function is dangerous and should not be used.