Compilare: user.cpp: In function ‘void Insert(Trie*, int)’: user.cpp:30:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (step==str.size()) ^ user.cpp: In function ‘bool Delete(int, Trie*)’: user.cpp:47:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (step==str.size()) ^ user.cpp: In function ‘int Query(std::string)’: user.cpp:69:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<S.size();++j) ^ user.cpp:66:11: warning: unused variable ‘t’ [-Wunused-variable] int j,t=0; ^ user.cpp: In function ‘int Prefix(Trie*, int, int)’: user.cpp:82:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (step==str.size() || !node->son[str[step]-'a']) ^ user.cpp: In function ‘int main()’: user.cpp:93:22: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[1000]’ [-Wformat=] scanf("%d%s",&type,&S); ^ user.cpp:117:26: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[1000]’ [-Wformat=] scanf("%d%s",&type,&S); ^ user.cpp:90:29: 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:91:31: 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:93:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%s",&type,&S); ^ user.cpp:117:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%s",&type,&S); ^