Compilare: main.cpp: In constructor 'trie_node::trie_node()': main.cpp:15:22: warning: passing NULL to non-pointer argument 2 of 'void* memset(void*, int, size_t)' [-Wconversion-null] 15 | memset(sons, NULL, sizeof(sons)); | ^~~~ In file included from /usr/include/c++/10/cstring:42, from main.cpp:4: /usr/include/string.h:61:37: note: declared here 61 | extern void *memset (void *__s, int __c, size_t __n) __THROW __nonnull ((1)); | ~~~~^~~ main.cpp: In function 'void trie_insert(trie_node*, const string&, int)': main.cpp:21:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 21 | if(pos >= s.size()){ | ~~~~^~~~~~~~~~~ main.cpp: In function 'void trie_erase(trie_node*, const string&, int)': main.cpp:38:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 38 | if(pos >= s.size()){ | ~~~~^~~~~~~~~~~ main.cpp: In function 'int get_frequency(trie_node*, const string&, int)': main.cpp:48:12: 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(pos >= s.size()){ | ~~~~^~~~~~~~~~~ main.cpp:54:16: warning: converting to non-pointer type 'int' from NULL [-Wconversion-null] 54 | return NULL; | ^~~~ main.cpp: In function 'int get_lcp(trie_node*, const string&, int)': main.cpp:60:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 60 | if(pos >= s.size()){ | ~~~~^~~~~~~~~~~