queue.cpp

#include <iostream>
#define E int
using namespace std;

typedef struct linked_list {
    struct linked_list * next;
    E element;
}Link ;

Link* creat_link(Link *nextval){
    Link *n = new Link;
    n->next = nextval;
    return n;
}

Link* create_link(E it, Link* nextval){
    Link *n = new Link;
    n->element = it;
    n->next = nextval;
    return n;
}

typedef struct q{
    Link *front;
    Link *rear;
    int size;
}queue;

queue* create_queue(){
    queue *q = new queue;
    q->front = q->rear = creat_link(NULL);
    q->size = 0;
    return q;
}

void enqueue(queue* q, E it){
    q->rear->next = create_link(it, NULL);
    q->rear = q->rear->next;
    q->size++;
}

E dequeue(queue* q){
    if(q->size == 0){
        printf("Erro!");
    }
    else{
        E it = q->front->next->element;
        q->front->next = q->front->next->next;
        if(q->front->next == NULL){
            q->rear = q->front;
        }
        q->size--;
        return it;
        
    }
}

void clear(queue *q){
    while (q->size>0){
        dequeue(q);
    }
    delete(q);
}