Creating a suffix tree in C ++

Question

I am trying to build a suffix tree in C ++ as part of a gene sequence assignment

void Tree::insert(string ins)  
{  
  Node* iterator = chooseBranch(root, ins.at(0));  
  string temp;  
  for(int i=0; i<100; i++)  
    {  
      if(iterator->data=="")  
.
.
.

chooseBranch()is a function to choose which of the four children to go to, and I'm trying to check if this Node exists. My Node Class:

struct Node{  
  Node();  
  string data;  
  Node* A;  
  Node* G;  
  Node* C;  
  Node* T;  
};

This if statement gives me the segfault that I used gdb to return:

#0  0x0000003ce249bbd6 in std::string::compare () from /usr/lib64/libstdc++.so.6
#1  0x000000000040185b in std::operator==<char, std::char_traits<char>, std::allocator<char> > ()
#2  0x0000000000401305 in Tree::insert ()
#3  0x00000000004016d4 in Tree::Tree ()
#4  0x00000000004010a2 in main ()

What is wrong with this form of checking NULL / how else can I check if Node has data?

Answer 1

It doesn't look like you are generally checking iteratorfor a pointer for NULL, you are just casting it (which will cause drama if it is NULL).

, , NULL, for:

void Tree::insert(string ins)
{
    Node* iterator = chooseBranch(root, ins.at(0));
    if (iterator)
    {
        string temp;
        for(int i=0; idata=="")
...