Queue Dynamic Array - c

Question

i am studying queue in c and trying to make basic queue program. But couldn't manage to allocate memory for my array. Here is my queue declaration and my createqueue function. After allocating memory space for myQueue, i should allocate for array aswell but i dont know how. Should i just type myQueue->array =(myQueue)malloc(sizeof(myQueue)); will it work ?
struct QueueRecord
{
int capacity;
int front;
int rear;
int size;
int *array;
};
typedef struct QueueRecord *Queue;
Queue CreateQueue(int maxElements)
{
Queue myQueue;
if (maxElements<MIN_QUEUE_SIZE)
{
printf("Queue is too small\n");
return;
}
myQueue = (Queue*)malloc(sizeof(Queue));
if (myQueue == NULL)
printf("out of memmory space");
myQueue->array =(myQueue)malloc(sizeof(myQueue));
myQueue->capacity=maxElements;
MakeEmptyQueue(myQueue);
return myQueue;
}

Answer 1

i should allocate for array aswell but i dont know how
because of the line
myQueue->capacity=maxElements;
the logic is to have
myQueue->array = malloc(sizeof(int) * maxElements);
Should i just type myQueue->array =(myQueue)malloc(sizeof(myQueue)); will it work ?
only in case sizeof(myQueue) is greater than sizeof(int) * maxElements, but you only check maxElements not too small, when maxElements is enough large the behavior is undefined (typically when maxElements is greater than 6 when the size of a pointer is the double of the size of an int).
Out of that :
It is a bad idea to have a typedef defining a pointer, better to have the pointers explicit in the code to see them
the first return; must be return NULL;
knowing myQueue is NULL do not dereference it after, you can directly return NULL after the printf
you check the first malloc does not return NULL, do also for the second, typically in the same if
For instance :
struct QueueRecord
{
int capacity;
int front;
int rear;
int size;
int *array;
};
typedef struct QueueRecord Queue;
void MakeEmptyQueue(Queue *);
Queue * CreateQueue(int maxElements)
{
Queue * myQueue;
if (maxElements < MIN_QUEUE_SIZE)
{
printf("Queue/maxElements is too small\n");
return NULL;
}
if (((myQueue = malloc(sizeof(Queue))) == NULL) ||
((myQueue->array = malloc(sizeof(int) * maxElements)) == NULL))
{
printf("out of memory space\n");
free(myQueue); /* to avoid memory leak, no problem if myQueue is NULL */
return NULL;
}
myQueue->capacity = maxElements;
MakeEmptyQueue(myQueue);
return myQueue;
}