Queue overhaul

Author: sunitgopal

queue.c

@@ -1,103 +1,118 @@
 #include "queue.h"
 
 
-
 int main(){
 
- Peek();
- Enqueue(7);
- Peek();
+ Queue_Type* q1 = create(q1);
+ Peek(q1);
+ Enqueue(q1, 7);
+ Peek(q1);
 
  int dequeued_val;
- Dequeue(&dequeued_val);
- Peek();
+ Dequeue(q1, &dequeued_val);
+ Peek(q1);
 
- Dequeue(&dequeued_val);
- Enqueue(2);
- Enqueue(4);
- Peek();
+ Dequeue(q1, &dequeued_val);
+ Enqueue(q1, 2);
+ Enqueue(q1, 4);
+ Peek(q1);
+ Dequeue(q1, &dequeued_val);
 
  return 0;
 }
 
-void Enqueue (int val){
+Queue_Type* create(Queue_Type* q){
+
+ q = (Queue_Type*) malloc (sizeof(Queue_Type));
+ 
+ if (NULL == q){
+
+ printf("create() unsuccessful due to malloc failure\n");
+ return NULL;
+ }
+ q->first = NULL;
+ q->last = NULL;
+ return q;
+}
+
+void Enqueue (Queue_Type* q, int val){
 
  QUEUEMEMBER* qmember = (QUEUEMEMBER*) malloc (sizeof(QUEUEMEMBER));
 
  if (NULL == qmember){
 
- printf ("Enqueue unsuccessful due to malloc() failure.\n");
+ printf ("Enqueue() unsuccessful due to malloc failure.\n");
  return;
  }
 
  qmember->data = val;
  qmember->ptr = NULL;
 
- if (NULL == first){
+ if (NULL == q->first){
 
- first = qmember;
+ q->first = qmember;
  }
- if (NULL == last){
+ if (NULL == q->last){
 
- last = first;
+ q->last = q->first;
  }
  else{
 
- last->ptr = qmember;
- last = qmember;
+ q->last->ptr = qmember;
+ q->last = qmember;
  }
 
  printf("Queue after Enqueue():\n");
- Print(first);
+ Print(q);
  return;
 }
 
-void Dequeue (int* dqd_val){
+void Dequeue (Queue_Type* q, int* dqd_val){
 
- if (NULL == first){
+ if (NULL == q->first){
 
  printf ("Empty Queue. Nothing to Dequeue\n");
  return;
  }
 
- QUEUEMEMBER* temp = first;
+ QUEUEMEMBER* temp = q->first;
 
- if (first == last){ // when there's only one item in Queue
+ if (q->first == q->last){ // when there's only one item in Queue
 
- last = NULL;
+ q->last = NULL;
  }
 
- first = first->ptr;
+ q->first = q->first->ptr;
 
  *dqd_val = temp->data;
 
  free(temp);
 
  printf("Queue after Dequeue():\n");
- Print(first);
+ Print(q);
  return;
 }
 
-void Peek(){
+void Peek(Queue_Type* q){
 
- if (NULL == first){
+ if (NULL == q->first){
  printf("Empty Queue. Nothing to peek\n");
  return;
  }
 
- printf("First item in Queue = %d\nLast item in Queue = %d\n", first->data, last->data);
+ printf("First item in Queue = %d\nLast item in Queue = %d\n", q->first->data, q->last->data);
 
  return;
 }
 
-void Print(QUEUEMEMBER* beg){
+void Print(Queue_Type* q){
 
- if (NULL == beg){
+ if (NULL == q->first){
  printf("Empty Queue. Nothing to print\n");
  return;
  }
 
- QUEUEMEMBER* iter = beg;
+ QUEUEMEMBER* iter = q->first;
 
  while(iter->ptr != NULL){
 

queue.h

@@ -1,17 +1,21 @@
 #ifndef QUEUE_H
 #define QUEUE_H
 
-#include "LL.h"
+#include "LL_shared.h"
 #include <stdio.h>
 
-typedef NODE QUEUEMEMBER; // alias for NODE
+typedef NODE QUEUEMEMBER;  // alias for NODE
 
-static QUEUEMEMBER* first = NULL; // first is the LL head node pointer
-static QUEUEMEMBER* last = NULL; // last is the LL tail node pointer
+typedef struct Queue{
+ QUEUEMEMBER* first;
+ QUEUEMEMBER* last;
+} Queue_Type;
 
-void Enqueue (int);
-void Dequeue (int*);
-void Peek (void);
-void Print(QUEUEMEMBER*); // for debug purposes // expects first pointer
+
+Queue_Type* create (Queue_Type*);
+void Enqueue (Queue_Type*, int);
+void Dequeue (Queue_Type*, int*);
+void Peek (Queue_Type*);
+void Print(Queue_Type*); // for debug purposes 
 
 #endif // QUEUE_H