I'm having trouble creating a Depth First Search for my program. So far I have a class of edges and a class of regions. I want to store all the connected edges inside one node of my region. I can tell if something is connected by the getKey() function I have already implemented. If two edges have the same key, then they are connected. For the next region, I want to store another set of connected edges inside that region, etc etc. However, I am not fully understanding DFS and I'm having some trouble implementing it. I'm not sure when/where to call DFS again. Any help would be appreciated!

class edge
{ 
  private:
  int source, destination, length;
  int key;
  edge *next;
  public:
  getKey(){ return key; } 
}

class region
{
   edge *data;
   edge *next;
   region() { data = new edge(); next = NULL; }

};

void runDFS(int i, edge **edge, int a)
{
  region *head = new region();
  aa[i]->visited == true;//mark the first vertex as true
  for(int v = 0; v < a; v++)
  {
    if(tem->edge[i].getKey() == tem->edge[v].getKey()) //if the edges of the vertex have the same root
    {
        if(head->data == NULL)
        {
          head->data = aa[i];
          head->data->next == NULL;
        } //create an edge
        if(head->data)
        {
          head->data->next = aa[i];
          head->data->next->next == NULL;
        }//if there is already a node connected to ti
    }
    if(aa[v]->visited == false)
      runDFS(v, edge, a); //call the DFS again
  } //for loop
 }