연결된큐

#include<stdio.h>
#include<stdlib.h>
#define MAX_QUEUE_SIZE 100


typedef struct LinkedNode {
	int data;
	struct LinkedNode* link;
} Node;
Node* front = NULL;
Node* rear = NULL;

void init_queue() { front = rear = NULL; }
int is_empty() { return front == NULL; }
int size() {
	Node* p;
	int count = 0;
	for (p = front; p != NULL; p = p->link) count++;
	return count;

}

void enqueue(int val) {
	Node* p = (Node*)malloc(sizeof(Node));
	p->data = val;
	p->link = NULL;
	if (is_empty()) front = rear = p;
	else {
		rear->link = p;
		rear = p;
	}
}

int dequeue() {
	int e = 0;
	if (!is_empty()) {
		Node* p = front;
		front = front->link;
		if (front == NULL) rear = NULL;
		e = p->data;
		free(p);
	}

	return e;
}

int peek() {
	if (!is_empty()) {
		return front->data;
	}
}

void destroy_queue() {
	while (!is_empty()) dequeue();
}

void print_queue(char msg[]) {
	Node* p;
	printf("%s[%2d]= ", msg, size());
	for (p = front; p != NULL; p = p->link) {
		printf("%2d ", p->data);
	}
	printf("\n");
}

void main() {
	int i;
	init_queue();
	for (int i = 1; i < 10; i++) {
		enqueue(i);
	}
	print_queue("연결된큐 equeue 9회");
	printf("\tdequeue() --> %d\n", dequeue());
	printf("\tdequeue() --> %d\n", dequeue());
	printf("\tdequeue() --> %d\n", dequeue());
	print_queue("연결된큐 dqueue 3회");
	destroy_queue();
	print_queue("연결된큐 destroy_queue ");
}