Compilare: user.cpp: In constructor ‘trie_node::trie_node()’: user.cpp:17:43: warning: converting to non-pointer type ‘short unsigned int’ from NULL [-Wconversion-null] back_node = NULL; cnt_occurrences = NULL; ^ user.cpp: In function ‘trie_node* insert_word(trie_node*, char*)’: user.cpp:28:18: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) { ^ user.cpp: In function ‘int count_occurrences(trie_node*, char*)’: user.cpp:41:18: warning: NULL used in arithmetic [-Wpointer-arith] if( *word == NULL ) ^ user.cpp: In function ‘void build_back_edges(trie_node*)’: user.cpp:57:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < node -> pos.size(); j ++ ) { ^ user.cpp: In function ‘void build_occurrences(trie_node*, char*)’: user.cpp:81:34: warning: NULL used in arithmetic [-Wpointer-arith] for( *word = *word; *word != NULL; word ++ ) { ^ user.cpp: In function ‘void build_partial_sum(trie_node*)’: user.cpp:96:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < node -> front_node.size(); i ++ ) { ^ user.cpp: In function ‘int main(int, const char**)’: user.cpp:126:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "seti.in" , "r", stdin ); ^ user.cpp:127:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "seti.out", "w", stdout ); ^ user.cpp:129:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d", &string_len ); ^ user.cpp:132:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%s", my_string + ((i - 1) << 6) ); ^ user.cpp:134:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d", &nr_words ); ^ user.cpp:138:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%s", word ); ^