Implementing a simple queue in C

Question

I am learning C and I have some trouble with pointers. I decided to create a queue to practice a bit. The program works as intended, however I want to know some good practices and suggestions.

Here is queue.c:

#include <stdlib.h>
#include "bank_sim.h" 
#include "queue.h"
void initiliaze(Queue *queue) {
 queue->head = NULL;
 queue->tail = NULL;
}
void enqueue(Queue *queue, Customer *customer) {
 if (queue->head == NULL) {
 queue->head = customer;
 queue->tail = customer;
 queue->customer_cnt++;
 } else {
 queue->tail->next = customer;
 queue->tail = customer;
 queue->customer_cnt++;
 }
}
Customer *dequeue(Queue *queue) {
 if (queue->head == NULL) {
 return NULL;
 } else {
 Customer *head_customer = queue->head;
 queue->head = queue->head->next;
 head_customer->next = NULL;
 queue->customer_cnt--;
 return head_customer;
 }
}

queue.h:

#ifndef QUEUE_H
#define QUEUE_H
#include "bank_sim.h"
typedef struct {
 Customer *head;
 Customer *tail;
 int customer_cnt;
} Queue;
void initiliaze(Queue *queue);
void enqueue(Queue *queue, Customer *customer);
Customer *dequeue(Queue *queue);
# endif

Finally bank_sim.h:

#ifndef BANK_SIM_H
#define BANK_SIM_H
typedef struct Customer Customer;
struct Customer {
 int id;
 int service_time;
 struct Customer *next;
};
typedef struct {
 Customer *customer;
 int occupied;
} Bank_Teller;
#endif

Comments regarding anything is welcome including whether my structure for Customer and Queue can be improved.

Answer 1

One major thing: Queue consists of node which consist of data. Here, your data is Customer. Data should not be coupled with the Queue i.e. think this way.

 typedef struct Node{
 Node* next; // navigation pointer.
 Customer customer; // data
 }Node;

Considering the current implementation, here are a few points to go with:

1. Initialize misses to initialize customer_cnt = 0;.

2. Where are you allocating the Queue instance. Instead, have getQueueNode which allocates memory for the node and initialise that as well. Allocation at one place helps for e.g: easy debugging when malloc returns null due to insufficient memory.

3. Extract common code outside the if-else block in enqueue().

4. Put related code at once i.e. in dequeue operations for head_customer could be consecutive.