Question

I’m trying to serialize my huffman tree to a file, but having issue with the recursive nature of the problem. I have no trouble printing it to console using cout, but I get segmentation fault when I try to store it in a string or write to a file.

string putData(Node *n, string &s) {

  if (n->leaf()) {
    s << "[" << n->value() << "]";
  } else {
    s << ".";
  }

  if (n->left())
    putData(n->left(), s);

  if (n->right())
    putData(n->right(), s);

}

It’s the same issue with an ofstream object. Actually, after the program segfaults, I check the file and its contents are proper. But why is it segfaulting at the end? How do I stop the program from segfaulting?

string putData(Node *n, ofstream &s) {

  s.open("huffout.txt", ios::app);

  if (n->leaf()) {
    s << "[" << n->value() << "]";
  } else {
    s << ".";
  }
  s.close()
  if (n->left())
    putData(n->left(), s);

  if (n->right())
    putData(n->right(), s);

}

Answer 1

Your function is declared to return string but has no return statement, if anything looks at the return value that could cause a segfault. Your compiler should have warned you about the missing return, aren’t you compiling with warnings?

Also, the first code example uses a string but tries to append to it with operator<<, presumably that’s just a copy’n’paste error.