如何通过引用传递 C++ 字符串？

Question

I am writing a huffcode program, and I'm going through every branch of the tree to to find the code for each alphabet. How can I pass the string to insert it? Also, Im getting errors from the way I declared my string vector, but Ive used vectors all over my code. Is there something I am doing wrong?

void treeTraverser(Node* root, char string, vector<char> const &alpha,
vector<string> const &huffcode){
 if(root->left!=NULL){
     string=string+'0';
     treeTraverser(root->left, string, alpha, huffcode);
  }
 if(root->right!=NULL){
    string=string+'1';
    treeTraverser(root->right, string, alpha, huffcode);
  }
   alpha.push_back(root->key);
   huffcode.push_back(string);
}

Answer 1

Change char to string& in your string parameter (and consider renaming it, too).

Also, get rid of the const on the huffcode parameter. You can't push_back() into a const vector object.

void treeTraverser(Node* root, string &str, vector<char> const &alpha, vector<string> &huffcode)
{
  if (root->left){
    str += '0';
    treeTraverser(root->left, str, alpha, huffcode);
  }
  if (root->right){
    str += '1';
    treeTraverser(root->right, str, alpha, huffcode);
  }
  alpha.push_back(root->key);
  huffcode.push_back(str);
}