c++ - get all words exist in trie using recursion -

i found function traverse trie , return list contains words exist in trie. problem can't make work me, appreciated.

class node {     public:         node();         node* ch[26];         bool isend; };  node::node() {     for(int = 0; < 26; i++)         ch[i] = null;     isend = 0; }   class trie {     public:         node* root;         trie() {root = new node();}         void insert(string word, node* ptr);         bool find(string word, node* ptr);         list<string> findwords(node* root); };  void trie::insert(string word, node* ptr) {     for(unsigned int = 0; < word.size(); i++) {         if(ptr->ch[word[i]-'a'] == null)             ptr->ch[word[i]-'a'] = new node();         ptr = ptr->ch[word[i]-'a'];     }     ptr->isend = 1; }  list<string> trie::findwords(node* ptr) {     list<string> result;      if(ptr->isend)         result.push_back("");      for(int = 0; < 26; i++)         if(ptr->ch[i] != null) {             ptr = ptr->ch[i];             list<string> childresult = findwords(ptr);             char letter = (char) (97 + i);             for(string sufix : childresult)                 result.push_back("" + letter + sufix);         }     copy(result.begin(),result.end(),ostream_iterator<string> (cout," "));     return result; } 

test main:

int main() {     trie t;     string word;     for(int = 0; < 10; i++) {         cin >> word;         insert(word, root);     }     system("pause");     return 0; }