Queue using Arrays

#include <stdio.h>
#include <stdlib.h>

struct queue
{
    int size;
    int f;
    int r;
    int* arr;
};

int isEmpty(struct queue *q){
    if(q->r==q->f){
        return 1;
    }
    return 0;
}

int isFull(struct queue *q){
    if(q->r==q->size-1){
        return 1;
    }
    return 0;
}

void enqueue(struct queue *q, int val){
    if(isFull(q)){
        printf("This Queue is full\n");
    }
    else{
        q->r++;
        q->arr[q->r] = val;
        printf("Enqued element: %d\n", val);
    }
}

int dequeue(struct queue *q){
    int a = -1;
    if(isEmpty(q)){
        printf("This Queue is empty\n");
    }
    else{
        q->f++;
        a = q->arr[q->f];
    }
    return a;
}
int main() {
   struct queue q;
   q.size=4;
   q.f= q.r = 0;
   q.arr = (int*) malloc(q.size*sizeof(int));
   
   enqueue(&q, 12);
   enqueue(&q, 15);
   enqueue(&q, 1);
   printf("Dequeuing element %d\n", dequeue(&q));
   printf("Dequeuing element %d\n", dequeue(&q));
   printf("Dequeuing element %d\n", dequeue(&q));
   enqueue(&q,45);
   enqueue(&q,45);
   enqueue(&q,45);
   
   if(isEmpty(&q)){
       printf("Queue is empty\n");
   }
   if(isFull(&q)){
       printf("Queue is full\n");
       
   }
   
    return 0;
}