?
Solved

pointer confusion in hash table

Posted on 2004-10-09
3
Medium Priority
?
223 Views
Last Modified: 2012-05-05
HI expert(s)

I am getting really confused with all the pointers for a school assignment, and is unable to get help on a weekend.
I have a set of structs containing a number of different pointers:

typedef struct bucket *ListPtr;
typedef struct bucket *BucketPtr;
typedef struct conListNode *ListNodePtr;

typedef struct ipaddr
{
  int digit1, digit2, digit3, digit4;
}IPAddress;

typedef struct bucket
{
  int           size;
  ListPtr       listPtr;
}Bucket;

typedef struct connctnList
{
  int         tableSize_N;
  int         bucketThreshold_m;
  int         primeNo1_k1;
  int         primeNo2_k2;
  int         primeNo3_k3;
  int         primeNo4_k4;
  int         primeNo5_k5;
  BucketPtr   *bucketPtr;
}connctnList;

typedef struct conListNode
{
  IPAddress     ipAddress;
  int           portNumber;
  ListNodePtr   next;
}ConListNode;

When I use them in a function, eg:

int addConnection(connctnList *conList, IPAddress address, int port)
{
  int hashValue = INITIALISE;
  BucketPtr position;
  ListNodePtr current, previous, new;
  ...
  if (position == NULL)
  {
    conList->bucketPtr[hashValue]->size++;
    position = new;  <---------------------------------------this line
    return SUCCESS;
  }

I get this message for the line pointed to by an arrow:

"connctnList_HT.c:258: warning: assignment from incompatible pointer type"

I know it is because BucketPtr and ListNodePtr are different pointer types, but how can I re-structure the ADTs to resolve this.

Thanks in advance

kwy
0
Comment
Question by:kwy
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 22

Accepted Solution

by:
cookre earned 2000 total points
ID: 12269293
If it's unhappy with an explicit cast:
position=(BucketPtr)new;

try it thru a void:
position=(BucketPtr)((void)new);
0
 

Author Comment

by:kwy
ID: 12269393
thanks, but why the void ??
0
 
LVL 22

Expert Comment

by:cookre
ID: 12269491
Sometimes a compiler simply won't do a cast from type A to type B, but it never has problems going to or from void, so we use that as an intermediate.
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Although it can be difficult to imagine, someday your child will have a career of his or her own. He or she will likely start a family, buy a home and start having their own children. So, while being a kid is still extremely important, it’s also …
Viewers will learn how to properly install Eclipse with the necessary JDK, and will take a look at an introductory Java program. Download Eclipse installation zip file: Extract files from zip file: Download and install JDK 8: Open Eclipse and …
Simple Linear Regression

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question