...
void spaces(int n)
{ for (int i=0; i<n; i+=1)
    cout << " "; }

void printlevel(StringTree * t, int level)
{ if (t==NULL)
    return;
  printlevel(t->left, level-1);
  if (level==0)
    cout << t->data;
  else
    spaces(t->data.length());
  printlevel(t->right, level-1); }

void print(StringTree * t, int maxlevels)
{ for (int i=0; i<maxlevels; i+=1)
  { printlevel(t, i);
    cout << "\n\n"; } }
...
...
    else if (command=="p")
    { print(tree, 10);
      cout << "\n"; }
...