Thread: Queue trouble!

Hey guys,

I am in the midsts of writing code that involves managing two queues of names, and having the ability to call one name from the queue, and then deleting it. For some reason, I can't get it to properly work. I was wondering if someone could look over these couple functions and see if you notice anything wrong with them.

Here's the two struct definitions:

Code:

#define MAX 50
#define EMPTY 0

struct elem {
   char name[MAX];
   struct elem *next;
};

struct queue {
   int num;
   struct elem *front;
   struct elem *rear;
};

Function enqueue:

Code:

void enqueue(queue *qu, char pass[]) {
   elem *p;

   strcpy(p->name, pass);
   p->next=NULL;
   if (!empty(qu)) {
      qu->rear->next = p;
      qu->rear = p;
   }
   else qu->front = qu->rear = p;
   printf("name = %s\n", qu->rear->name);
   qu->num++;
}

Function dequeue:

Code:

char *dequeue(queue *qu) {
   char *pass = malloc(sizeof(char)*50);
   elem *p;

   p = qu->front;
   strcpy(pass, qu->front->name);
   qu->front = qu->front->next;
   qu->num--;
   free(p);
   return (pass);
}

I also have:

Code:

typedef struct queue queue;
typedef struct elem elem;

Now, what seems to happen is that when I call dequeue, the name it gives me is always the last name I add to either queue. I can't seem to get it to work.

No ideas?

Ahha, that did it. I could have sworn I had the code to alloc the memory in there before.. must have lost it in my many attempts to fix the code after the first run through. Thanks again!