Compilare: user.cpp: In function ‘int main()’: user.cpp:70:25: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘char (*)[21]’ [-Wformat=] scanf("%s", &str); ^ user.cpp: In function ‘int apar(Trie*, char*)’: user.cpp:54:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int pref(Trie*, char*, int)’: user.cpp:61:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:64:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.in", "r", stdin); ^ user.cpp:65:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.out", "w", stdout); ^ user.cpp:70:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s", &str); ^