链式队列

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

#define QUEUE_DEBUG  1

typedef struct _qnode_ {
    int data;
    struct _qnode_ *next;
}qnode_t;

typedef struct _queue_ {
    qnode_t *head;
    qnode_t *tail;
    int clen;
    int tlen;
}queue_t;

queue_t *queue_init(int len);
qnode_t *create_qnode(int value);
int queue_destory(queue_t *queue);
int queue_enqueue(queue_t *queue, int value);
int queue_dequeue(queue_t *queue, int *value);
int queue_isfull(queue_t *queue);
int queue_isempty(queue_t *queue);
#if QUEUE_DEBUG
void _queue_debug_(queue_t *queue);
#endif

int main()
{
    int value = 100;
    queue_t *queue = NULL;

    queue = queue_init(10);

    puts("Enqueue:");
    while (0 == queue_enqueue(queue, value)) {
        printf("%5d", value);
        value += 100;
    }
    putchar('\n');

#if QUEUE_DEBUG
    _queue_debug_(queue);
#endif

    puts("Dequeue:");
    while (0 == queue_dequeue(queue, &value))
        printf("%5d", value);
    putchar('\n');

#if QUEUE_DEBUG
    _queue_debug_(queue);
#endif

    queue_destory(queue);

    return 0;
}

queue_t *queue_init(int len)
{
    queue_t *queue = NULL;

    queue = (queue_t *)malloc(sizeof(queue_t));
    queue->tlen = len;
    queue->clen = 0;
    queue->head = create_qnode(0);
    queue->tail = queue->head;

    return queue;
}

int queue_destory(queue_t *queue)
{
    qnode_t *p = queue->head;
    qnode_t *tmp = NULL;

    while (NULL != p) {
        tmp = p;
        p = p->next;
        free(tmp);
        tmp = NULL;
    }
    free(queue);
}

qnode_t *create_qnode(int value)
{
    qnode_t *node = NULL;

    node = (qnode_t *)malloc(sizeof(qnode_t));
    node->data = value;
    node->next = NULL;

    return node;
}

int queue_enqueue(queue_t *queue, int value)
{
    if (queue_isfull(queue))
        return -1;

    qnode_t *new = NULL;
    new = create_qnode(value);
    queue->tail->next = new;
    queue->tail = new;

    queue->clen++;

    return 0;
}

int queue_dequeue(queue_t *queue, int *value)
{
    qnode_t *p = queue->head;

    if (queue_isempty(queue))
        return -1;

    queue->head = p->next;
    free(p);

    *value = queue->head->data;
    queue->clen--;

    return 0;
}

int queue_isfull(queue_t *queue)
{
    if (queue->clen >= queue->tlen)
        return 1;
    return 0;
}

int queue_isempty(queue_t *queue)
{
    if (queue->head == queue->tail)
        return 1;
    return 0;
}

#if QUEUE_DEBUG
void _queue_debug_(queue_t *queue)
{
    qnode_t *p = queue->head->next;
    puts("------------------ QUEUE_DEBUG ------------------");
    printf("tlen: %d\tclen: %d\n", queue->tlen, queue->clen);
    while (NULL != p) {
        printf("%5d", p->data);
        p = p->next;
    }
    puts("\n-------------------------------------------------");
}
#endif