edge.c

Go to the documentation of this file.

#include "basic.h"
#include "edge.h"

edgelist NullEdgeList = {NULL, NULL, 0};


int AddEdge(edgelist *List, int x1, int y1, int x2, int y2)
{
    edge *NewEdge;
    
    if(!List || !(NewEdge = (edge *)Malloc(sizeof(edge))))
        return 0;
    
    NewEdge->x1 = x1;
    NewEdge->y1 = y1;
    NewEdge->x2 = x2;
    NewEdge->y2 = y2;
    NewEdge->Weight = 1;
    NewEdge->NextEdge = NULL;
        
    if(!List->Tail) /* Add edge to empty list */
        List->Head = List->Tail = NewEdge;
    else            /* Append the edge to the end of the list */
    {
        List->Tail->NextEdge = NewEdge;
        List->Tail = NewEdge;
    }
    
    (List->NumEdges)++;
    return 1;
}


void FreeEdgeList(edgelist *List)
{
    edge *Edge, *NextEdge;
    
    for(Edge = List->Head; Edge; Edge = NextEdge)
    {
        NextEdge = Edge->NextEdge;
        Free(Edge);
    }
    
    List->Head = List->Tail = NULL;
    List->NumEdges = 0;
}