Compilare: user.cpp: In function ‘void add(std::string&, int, trie*)’: user.cpp:18:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size()){ ^ user.cpp: In function ‘int nr(std::string&, int, trie*)’: user.cpp:29:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size()){ ^ user.cpp: In function ‘int tip(std::string&, int, trie*)’: user.cpp:36:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size()){ ^ user.cpp: In function ‘int fct(std::string&, std::string&, int, trie*)’: user.cpp:43:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size() || j==b.size()){ ^ user.cpp:43:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size() || j==b.size()){ ^ user.cpp: In function ‘bool del(std::string&, int, trie*)’: user.cpp:50:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == a.size()) --c->cnt; ^