Compilare: main.cpp: In constructor 'trie::trie()': main.cpp:17:52: warning: passing NULL to non-pointer argument 2 of 'void* memset(void*, int, size_t)' [-Wconversion-null] memset(this->next, NULL, sizeof(this->next)); ^ main.cpp: In function 'void task::add(trie*, std::__cxx11::string&, int)': main.cpp:28:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i == sir.length()) ~~^~~~~~~~~~~~~~~ main.cpp: In function 'void task::erase(trie*&, std::__cxx11::string&, int)': main.cpp:44:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == sir.length()) ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int task::how_many(trie*, std::__cxx11::string&, int)': main.cpp:63:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == sir.length()) ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int task::get_prefix(trie*, std::__cxx11::string&, int)': main.cpp:74:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i < sir.length()) ~~^~~~~~~~~~~~~~