Compilare: user.cpp: In constructor ‘state_machine::trie::trie()’: user.cpp:38:23: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] cnt_words = NULL; ^ user.cpp:39:26: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] cnt_children = NULL; ^ user.cpp:40:29: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] cnt_occurrences = NULL; ^ user.cpp: In member function ‘void state_machine::insert_word(state_machine::trie*, char*)’: user.cpp:52:24: warning: NULL used in arithmetic [-Wpointer-arith] if( *String == NULL ) { ^ user.cpp: In member function ‘int state_machine::delete_word(state_machine::trie*, char*)’: user.cpp:68:24: warning: NULL used in arithmetic [-Wpointer-arith] if( *String == NULL ) Node -> cnt_words --; else ^ user.cpp:72:50: warning: NULL used in arithmetic [-Wpointer-arith] if( Node != Root && Node -> cnt_words == NULL && Node -> cnt_children == NULL ) { ^ user.cpp:72:82: warning: NULL used in arithmetic [-Wpointer-arith] if( Node != Root && Node -> cnt_words == NULL && Node -> cnt_children == NULL ) { ^ user.cpp: In member function ‘int state_machine::count_word(state_machine::trie*, char*)’: user.cpp:82:24: warning: NULL used in arithmetic [-Wpointer-arith] if( *String == NULL ) ^ user.cpp: In member function ‘int state_machine::longest_prefix(state_machine::trie*, char*, int)’: user.cpp:93:24: warning: NULL used in arithmetic [-Wpointer-arith] if( *String == NULL ) ^ user.cpp: In member function ‘void state_machine::reset_machine(state_machine::trie*)’: user.cpp:103:33: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] Node -> cnt_occurrences = NULL; ^ user.cpp: In member function ‘void state_machine::build_occurrences(state_machine::trie*, char*)’: user.cpp:147:24: warning: NULL used in arithmetic [-Wpointer-arith] if( *String == NULL ) ^ user.cpp: In member function ‘void state_machine::build_partial_sum(state_machine::trie*)’: user.cpp:164:53: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < Node -> front_node.size(); i ++ ) { ^ user.cpp: In member function ‘int state_machine::count_occurrences(state_machine::trie*, char*)’: user.cpp:174:24: warning: NULL used in arithmetic [-Wpointer-arith] if( *String == NULL ) ^ user.cpp: In function ‘int main()’: user.cpp:219:46: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]