C语言用链表实现队列_c链表队列

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

//用链表实现队列

typedef int E;
typedef struct node_s {
	E val;
	struct node_s* next;
 }Node;

typedef struct queue_s {
	Node* head;
	Node* tail;
}Queue;

Queue* Queue_create() {
	return (Queue*)calloc(1, sizeof(Queue));
}

void Queue_destory(Queue* q) {
	Node* curr = q->head;
	while (curr != NULL) {
		Node* next = curr->next;
		free(curr);
		curr = next;
	}
	free(q);
}

bool isEmpty(Queue* q) {
	return q->head == NULL;
}

void enqueque(Queue* q, E val) {
	Node* newNode = (Node *) malloc(sizeof(Node));
	if (newNode == NULL) {
		printf("Error: malloc failed in enqueque.\n");
		exit(1);
	}
	//初始化结点
	newNode->val = val;
	newNode->next = NULL;

	if (q->tail == NULL) {
		//插入第一个结点
		q->head = q->tail = newNode;
	}
	else {
		q->tail->next = newNode;
		q->tail = newNode;
	}
}

E dequeue(Queue* q) {
	if (isEmpty(q)) {
		printf("Errpr: queue is empty.\n");
		exit(1);
	}
	Node* node = q->head;
	E removeValue = node->val;

	q->head = node->next;
	if (q->head == NULL) {
		q->tail = NULL;
	}
	free(node);
	return removeValue;
}

E peek(Queue* q) {
	if (isEmpty(q)) {
		printf("Error: queue is empty.\n");
		exit(1);
	}
	return q->head->val;
}

int main(void) {
	
	Queue* q = Queue_create();

	enqueque(q, 1);
	enqueque(q, 2);
	enqueque(q, 3);

	dequeue(q);
	peek(q);

	Queue_destory(q);
	return;

}
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