Queue implementation in C

queue.c

#include<stdio.h>
#include<stdlib.h>
#define INT_MIN -999999

struct Queue{
    unsigned int capacity;
    int *arr;
    int front;
    int top;
    int size;
};

struct Queue *queue(unsigned int capacity){
    struct Queue *q = (struct Queue*)malloc(sizeof(struct Queue));
    q->capacity = capacity;
    q->top = -1;
    q->front = 0;
    q->size = 0;
    q->arr = (int*)malloc(capacity*sizeof(int));
    return q;
}

int isFull(struct Queue *queue){
    return queue->size == queue->capacity;
}

int isEmpty(struct Queue *queue){
    return queue->size == 0;
}

void eneque(struct Queue *queue, int data){
    if(isFull(queue))
    return;
    queue->arr[++queue->top % queue->capacity] = data;
    queue->size += 1;
    printf("The %d pushed into queue\n",data);
}

int deque(struct Queue *queue){
    if(isEmpty(queue))
    return INT_MIN;
    int data = queue->front;
    queue[++queue->front % queue->capacity];
    queue->size -= 1;
    return data;
}

int rear(struct Queue *queue){
    if(isEmpty(queue))
    return INT_MIN;
    return queue->arr[queue->top];
}

int front(struct Queue *queue){
    if(isEmpty(queue))
    return INT_MIN;
    return queue->arr[queue->front];
}


int main()
{
    int capacity = 100;
    struct Queue *q = queue(100);
    eneque(q, 10);
    eneque(q, 20);
    eneque(q, 30);
    eneque(q, 40);
    printf("Front: %d\n",front(q));
    printf("Rear: %d\n",rear(q));
    deque(q);
    deque(q);
    deque(q);
    printf("Front: %d\n",front(q));
    printf("Rear: %d\n",rear(q));
}