有没有一种实现类似 ringbuffer，但返回数据长度和传入时候一样

发布于 2020-11-06 16:09:44 浏览：1353 订阅该版

2 个回答

mysterywolf 认证专家 2020-11-06

https://github.com/mysterywolf

小住住 2020-11-06

这家伙很懒，什么也没写！

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小住住 认证专家 2020-11-07

这家伙很懒，什么也没写！

自己简单实现了一个，供大家参考：
queue.c
```
#include "queue.h"
#include <malloc.h>
#include <memory.h>

#define MAXQSIZE 100
#define MSG_MAX_SIZE 2048

typedef struct queueElement
{
    unsigned char msg[MSG_MAX_SIZE];
    int msg_size;
}queueElementT;

struct queueCDT{
    queueElementT *data;
    int front;
    int rear;

};

queueADT newQueue(void)
{
    queueADT queue;
    queue = (queueADT)malloc(sizeof (struct queueCDT));
    queue->data = (queueElementT *)malloc(MAXQSIZE * sizeof(queueElementT));
    queue->front = 0;
    queue->rear = 0;
    return queue;
}
void freeQueue(queueADT queue)
{
    free(queue->data);
    free(queue);
}

bool inQueue(queueADT queue, unsigned char *msg, int msg_len)
{
    if (queueIsFull(queue))
    {
        return ERROR_QUEUE_FULL;
    }
    memcpy(queue->data[queue->rear].msg,msg, msg_len);
    queue->data[queue->rear].msg_size = msg_len;
    queue->rear = (queue->rear + 1) % MAXQSIZE;
    return true;
}

bool outQueue(queueADT queue, unsigned char *msg, int *msg_len)
{
    if (queueIsEmpty(queue))
    {
        return ERROR_QUEUE_EMPTY;
    }
    memcpy(msg, queue->data[queue->front].msg, queue->data[queue->front].msg_size);
    *msg_len = queue->data[queue->front].msg_size;
     queue->front = (queue->front + 1) % MAXQSIZE;

return true;
}

bool queueIsEmpty(queueADT queue)
{
    return (queue->rear == queue->front);
}
//当front 在rear 的下一个位置 就视为队列已满 
bool queueIsFull(queueADT queue)
{
    return ((queue->rear + 1) % MAXQSIZE == queue->front);
}

size_t getQueueLength(queueADT queue)
{
    return (queue->rear -queue->front + MAXQSIZE) % MAXQSIZE;
}
```
queue.h
```
#pragma once
#include <stdbool.h>
#include <stddef.h>

#define ERROR_QUEUE_FULL   400 + 1
#define ERROR_QUEUE_EMPTY  400 + 2
// struct queueElement
// {
//     unsigned char data_msg[MSG_MAX_SIZE];
//     int data_msg_size;
// };
// typedef queueElement queueElementT;
//typedef int queueElementT;
typedef struct queueCDT *queueADT;

queueADT newQueue(void);
void freeQueue(queueADT queue);
bool inQueue(queueADT queue, unsigned char *msg , int msg_len);
bool outQueue(queueADT queue, unsigned char *msg, int *msg_len);
//bool queuelIsEmpty(queueADT queue);
bool queueIsEmpty(queueADT queue);

bool queueIsFull(queueADT queue);
size_t getQueueLength(queueADT queue);

```
queuetest.c
```
#include <stdio.h>

#include "queue.h"
//一个线程 塞数据  一个线程  取数据 
int main (int argc, int *argv[])
{
    queueADT queue;
    unsigned char data1[512] = {0};
    int data1_len = 512;
    unsigned char data2[128] = {0};
    int data2_len = 128;
    unsigned char data3[256] = {0};
    int data3_len = 256;
    unsigned char temp_data[1024] = {0};
    int temp_len = 0;
    int temp,i;
    int queue_len = 0;
    queue = newQueue();
    for (i = 0; i < 100; i++)
    {
        data1[i] = i;
    }
    for (i = 0; i< 100; i++)
    {
        data2[i] = i + 100;
    }
    for (i = 0; i< 100; i++)
    {
        data3[i] =  i + 100 + 100;
    }
    inQueue(queue, data1, 100);
    inQueue(queue, data2, 90);
    inQueue(queue, data3, 50);
    queue_len = getQueueLength(queue);
    printf("the queue len is %d\n", queue_len);
    outQueue(queue, temp_data, &temp_len);
    printf("the output queue len is %d\n", temp_len);
    for (i = 0; i < temp_len; i++)
    {
        printf("%d ", temp_data[i]);
    }
    printf("\n");

outQueue(queue, temp_data, &temp_len);
    printf("the output2 queue len is %d\n", temp_len);
    for (i = 0; i < temp_len; i++)
    {
        printf("%d ", temp_data[i]);
    }
    printf("\n");

outQueue(queue, temp_data, &temp_len);
    printf("the output3 queue len is %d\n", temp_len);
    for (i = 0; i < temp_len; i++)
    {
        printf("%d ", temp_data[i]);
    }
    printf("\n");
    
    queue_len = getQueueLength(queue);
    printf("the queue len is %d\n", queue_len);

freeQueue(queue);
    return 0;

}
```

![image.png](/uploads/20201107/6486ed1821125bfb1d188303349574dd.png)