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implemention of FIFO Queue

Discussion in 'C' started by newmember, May 2, 2012.

  1. newmember

    newmember New Member

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    can I improve/fix my implemention?
    I only implemented - Creatre/IsEmpty/Enqueue/Dequeue.
    Code:
    #include <stdlib.h>
    
    /*a link in the queue, holds the info and point to the next Node*/
    typedef struct Node_t{
            int count;
            Node_t *next;
    } Node;
    
    /*the HEAD of the Queue, hold the amount of node's that are in the queue*/
    typedef struct Queue{
            Node *head;
            Node *tail;
            unsigned int size;
    } Queue;
    
    void Create(){
         Queue *queue = (Queue*)malloc(sizeof(Queue));
         if (queue == NULL) return;
         queue->size = 0;
         queue->head = NULL;
         queue->tail = NULL;
    }
    
    bool Enqueue(Queue *pQueue, Node *item) {
         /*bad param*/
         if ((pQueue == NULL) ||(item == NULL)) return false;
         /*the queue is empty*/
         if (pQueue->size == 0) {
            pQueue->head = item;
         }
         /*adding item to the end of the queue*/
         pQueue->tail->next = item; 
         pQueue->size++;
         return true;
    }
    
    bool freeNode(Queue *pQueue) {
    		 Node *tmp = (pQueue->head)->next;
    		 free(pQueue->head);
    		 pQueue->head = tmp;
    		 return true;		      
    }
    
    bool Dequeue(Queue *pQueue, Node **item) {
         /*the queue is empty or bad param*/
         if ((pQueue->size == 0) || (pQueue == NULL) ||(*item == NULL)) return false;     
         *item = pQueue->head;
         if (freeNode(pQueue) == true) {
            pQueue->size--;
            return true;
         } else return false;
         
    }
    
    bool isEmpty(Queue* pQueue) {
         if (pQueue == NULL) return false;
         if (pQueue->size == 0) return true;
    		 else return false;
    }
     
  2. newmember

    newmember New Member

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    i have a problem with the function "Dequeue". I CAN'T seem to extract the information from the node I remove from the queue.
    I added a simple example - function main() - to help you understand what I mean.
    Code:
    #include <stdlib.h>
    #include <stdio.h>
    
    /*a link in the queue, holds the info and point to the next Node*/
    typedef struct Node_t{
            int info;
            Node_t *next;
    } Node;
    
    /*the HEAD of the Queue, hold the amount of node's that are in the queue*/
    typedef struct Queue_t{
            Node *head;
            Node *tail;
            unsigned int size;
    } Queue;
    
    Queue* Create(){
         Queue *queue = (Queue*)malloc(sizeof(Queue));
         if (queue == NULL) return NULL;
         queue->size = 0;
         queue->head = NULL;
         queue->tail = NULL;
         return queue;
    }
    
    bool Enqueue(Queue *pQueue, Node *item) {
         /*bad param*/
         if ((pQueue == NULL) ||(item == NULL)) return false;
         /*adding item to the end of the queue*/
         if (pQueue->size != 0) {
         		(pQueue->tail)->next = item;
         		pQueue->tail = item;
    		 } else {
    		 	  /*the queue is empty*/
            pQueue->head = pQueue->tail = item;
         }; 
         pQueue->size++;
         return true;
    }
    
    bool freeNode(Queue *pQueue) {
    		 Node *tmp = (pQueue->head)->next;
    		 free(pQueue->head);
    		 pQueue->head = tmp;
    		 return true;		      
    }
    
    bool Dequeue(Queue *pQueue, Node **item) {
         /*the queue is empty or bad param*/
         if ((pQueue->size == 0) || (pQueue == NULL) ||(*item == NULL)) return false;     
         *item = pQueue->head;
         if (freeNode(pQueue)) {
            pQueue->size--;
            return true;
         } else return false;    
    }
    
    bool isEmpty(Queue* pQueue) {
         if (pQueue == NULL) return false;/*bad param*/
         if (pQueue->size == 0) return true;
    		 else return false;
    }
         
    int main() {
    		bool b;
    		Queue *q;
    		/*creating the QUEUE of the queue*/
    		q = Create();
    		/*checking if queue is empty*/
    	 	if (isEmpty(q)) {printf ("Queue is Empty\n"); }
    	 	else {printf ("Queue is not empty\n");}
    		/*creating Node1 and insert it to the queue*/
    		Node *item1 = (Node*)malloc(sizeof(Node));
    		item1->info = 1;
    		item1->next = NULL;
    		Enqueue(q, item1);
      	/*creating Node2 and insert it to the queue*/
    		Node *item2 = (Node*)malloc(sizeof(Node));
    		item2->info = 2;
    		item2->next = NULL;
    		Enqueue(q, item2); 
    		/*removing the 1 node from the queue*/
    		Node *tmp = (Node*)malloc(sizeof(Node));
    	  Dequeue(q, &tmp); /*not working right*/
     	 	/*checking if queue is empty*/ 	 
    	 	if (isEmpty(q)) {printf ("Queue is Empty\n"); }
    	 	else {printf ("Queue is not empty\n");}
    	 	printf("info - %d\n", &tmp->info);
    		system ("pause");
    		return 0;
    }
     

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