Binary Search Tree output in tree structure - c++

Question

I used the code from this post, How to display binary search tree in console properly?. It complies fine on my IDE, but it doesnt print out anything so it basically shows nothing. I want it to print out in the tree structure like the post mentioned I posted here. I think I have the code typed wrong for 3rd argument for the printLevel function in int main(). Would char* x = " " work fine? It does give warning message, but I'm not sure if I do it right.
string printLevel(Node *pRoot, int level, string gap)
{
if (level == 1)
{
if (pRoot == 0)
{
cout << ".. printLevel - " << pRoot << ": " << gap << "-" << gap << "\n";
return gap + "-" + gap;
}
stringstream out;
out << pRoot->data;
//cout << ".. printLevel - " << pRoot << ": " << gap << pRoot->data << gap << "\n";
return gap + out.str() + gap;
}
else if(level > 1)
{
string left = printLevel(pRoot ? pRoot->pLeft : 0, level - 1, gap);
string right = printLevel(pRoot ? pRoot->pRight : 0, level - 1, gap);
//cout << ".. printLevel - " << pRoot << ": '" << left << "', '" << right << "'\n";
return left + " " + right;
}
else return
"";
}
void printLevelOrder(Node* pRoot, int depth)
{
for (int i = 1; i <= depth; i++)
{
string gap = "";
for (int j = 0; j < pow(2, depth - i) - 1; j++)
{
gap += " ";
}
string levelNodes = printLevel(pRoot, i, gap);
cout << levelNodes <<endl;
}
}
in the main
Node *pRoot = NULL;
int inputValue = 0;
char* gap = " ";
// Loop to read in input values
cout << "To build a BST enter positive integer values, followed by -1 \n";
while (inputValue != -1)
{
cin >> inputValue;
if( inputValue != -1)
{
insertIntoTree( pRoot, inputValue);
}
}
cout << endl;
// Display the tree
printLevel(pRoot, inputValue, gap);
printLevelOrder(pRoot, inputValue);