Compilare: main.cpp: In function 'void add_word(std::string&, int, trie_node*)': main.cpp:28:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 28 | if(index == word.size()) | ~~~~~~^~~~~~~~~~~~~~ main.cpp: In function 'void delete_word(std::string&, int, trie_node*)': main.cpp:48:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 48 | if(index == word.size()) | ~~~~~~^~~~~~~~~~~~~~ main.cpp: In function 'int count_word(std::string&, int, trie_node*)': main.cpp:66:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 66 | if(index == word.size()) | ~~~~~~^~~~~~~~~~~~~~ main.cpp: In function 'int longest_common_prefix_for_word(std::string&, int, trie_node*)': main.cpp:76:39: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 76 | if( current_node == NULL or index == word.size()) | ~~~~~~^~~~~~~~~~~~~~