Compilare: user.cpp: In function ‘void add(std::string&, int, trie*)’: user.cpp:26:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j < a.size()) p = (int)a[j]<97 ? (int)a[j]+32 : (int)a[j]; ^ user.cpp:27:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j != a.size())if (p < 97 || p>122) return; ^ user.cpp:28:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size()){ ^ user.cpp: In function ‘std::string tip(std::string&, int, trie*)’: user.cpp:43:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j< a.size() && !c->childs[p - 'a']) return "Search Bing for " + a; ^ user.cpp:47:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (j == a.size()){ ^ user.cpp: In function ‘void ModRel(std::string&, const int&, int, trie*)’: user.cpp:57:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size()){ ^ user.cpp: In function ‘void add(std::string&, int, trie*)’: user.cpp:32:24: warning: ‘p’ may be used uninitialized in this function [-Wmaybe-uninitialized] else if (!c->childs[p - 'a']){ ^