Queue Data Structure

queue.c

/**
 *  Queue Data Structure implemented as Array
 */
#include <stdio.h>
#define QUEUE_MAX 5

//declare my queue and two pointers to this data structure
int queue[ QUEUE_MAX ],
    front = -1,
    rear = -1;

//add new elements in the Queue;
void enQueue(int val) {

     //checks if the queue is full
     if(rear == QUEUE_MAX - 1) {
 
        fprintf(stderr, "%s\n", "Error: Queue overflow! I mean the Queue is full!");  

     } else {
           
            printf("Added: %d\n", val);
 
            if(front == -1) front = 0;

            rear++;

            queue[rear] = val;
     }

}


//remove elements from Queue;
int deQueue() {

     //check if the queue is empty
     if(front == -1) {
  
        fprintf(stderr, "%s", "Error: Queue is empty!");  

     } else {

         int tmp = queue[front];

             front++;

             if(front > rear) front = rear = -1;

             printf("Deleted: %d\n", tmp);
 
             return tmp;           
     }  

} 

int main() {

    enQueue(1);
    enQueue(5);
    enQueue(34);
    enQueue(41);
    enQueue(50);
    enQueue(6);

    deQueue();
    deQueue();
    deQueue();
    deQueue();
    deQueue();
    deQueue();     
return(0);
}