Create CircularQueue.c

Author: hjain5164

Data Structures/Queue/CircularQueue.c

@@ -0,0 +1,99 @@
+#include <stdio.h>
+
+#define SIZE 5
+
+int items[SIZE];
+int front = -1, rear =-1;
+
+int isFull()
+{
+    if( (front == rear + 1) || (front == 0 && rear == SIZE-1)) return 1;
+    return 0;
+}
+
+int isEmpty()
+{
+    if(front == -1) return 1;
+    return 0;
+}
+
+void enQueue(int element)
+{
+    if(isFull()) printf("\n Queue is full!! \n");
+    else
+    {
+        if(front == -1) front = 0;
+        rear = (rear + 1) % SIZE;
+        items[rear] = element;
+        printf("\n Inserted -> %d", element);
+    }
+}
+
+
+int deQueue()
+{
+    int element;
+    if(isEmpty()) {
+        printf("\n Queue is empty !! \n");
+        return(-1);
+    } else {
+        element = items[front];
+        if (front == rear){
+            front = -1;
+            rear = -1;
+        } /* Q has only one element, so we reset the queue after dequeing it. ? */
+        else {
+            front = (front + 1) % SIZE;
+            
+        }
+        printf("\n Deleted element -> %d \n", element);
+        return(element);
+    }
+}
+
+
+
+
+void display()
+{
+    int i;
+    if(isEmpty()) printf(" \n Empty Queue\n");
+    else
+    {
+        printf("\n Front -> %d ",front);
+        printf("\n Items -> ");
+        for( i = front; i!=rear; i=(i+1)%SIZE) {
+            printf("%d ",items[i]);
+        }
+        printf("%d ",items[i]);
+        printf("\n Rear -> %d \n",rear);
+    }
+}
+
+int main()
+{
+    // Fails because front = -1
+    deQueue();
+    
+    enQueue(1);
+    enQueue(2);
+    enQueue(3);
+    enQueue(4);
+    enQueue(5);
+    
+    // Fails to enqueue because front == 0 && rear == SIZE - 1
+    enQueue(6);
+    
+    display();
+    deQueue();
+    
+    display();
+    
+    enQueue(7);
+    display();
+    
+    // Fails to enqueue because front == rear + 1
+    enQueue(8);
+    
+    return 0;
+}