删除所有virtualenv并从头开始(Delete all virtualenv and start from scratch)

 我不明白你的意思是“不知道长度”，如果你传递每个缓冲区的大小和缓冲区的数量作为输入参数，那么你就知道每个所需的长度。 
 
 也许这不是最好的，但这将是我的方式。 
 
 首先声明全局缓冲区和线程。 
 
static void ** buffer;
pthread_t tid[2];
 
 这里描述了线程如何工作。 第一个缓冲区将为数据分配前两个子缓冲区。 第二个将与其他两个相同。 
 
void *assignBuffer(void *threadid) {

    pthread_t id = pthread_self();

    if (pthread_equal(id, tid[0])) {
        strcpy(buffer[0], "foo");
        strcpy(buffer[1], "bar");
    } else {
        strcpy(buffer[2], "oof");
        strcpy(buffer[3], "rab");
    }
    return NULL;
}
 
 
 
 将程序args从字符串转换为整数。 
 
 
 这里我们为缓冲区分配未知类型的数组。 
 
 
 这里我们为每个缓冲区分配大小（以字节为单位） 
 
 
 最后我们创建工作线程。 重要的是它们会同时运行。 
 
 
 等到所有线程完成他们的工作。 
 
 
 简单的打印缓冲区内容 
 
 
 好的，这是代码。 
 
int main(int argc, char **argv) {
    //1
    int bufferSize = atoi(argv[1]);
    int buffersAmount = atoi(argv[2]);

    //2
    buffer = malloc(sizeof(void *)*buffersAmount);

    //3
    int i;
    for (i = 0; i < buffersAmount; ++i) {
        buffer[i] = malloc(bufferSize);
    }

    //4
    i = 0;
    while (i < 2) {
        pthread_create(&tid[i], NULL, &assignBuffer, NULL);
        ++i;
    }

    //5
    for (i = 0; i < 2; i++)
        pthread_join(tid[i], NULL);

    //6
    for (i = 0; i < 4; ++i) {
        printf("%d %s\n", i, (char*)buffer[i]);
    }
    for (i = 0; i < buffersAmount; ++i) {
        free(buffer[i]);
    }
    return 0;
}
 
 随意问你是否理解不对，也对我的英语不好意思，这不是我的母语。 

I don't understand what do you mean by "without knowing length", if you pass size of each buffer and number of buffers as input parameters then you know every required length.
 
Maybe this is not the best, but that would be my way.
 
First declare global buffer and threads. 
 
static void ** buffer;
pthread_t tid[2];
 
Here is described how the threads will work. First buffer will assign with data first two sub-buffers. Second will do the same with the other two.
 
void *assignBuffer(void *threadid) {

    pthread_t id = pthread_self();

    if (pthread_equal(id, tid[0])) {
        strcpy(buffer[0], "foo");
        strcpy(buffer[1], "bar");
    } else {
        strcpy(buffer[2], "oof");
        strcpy(buffer[3], "rab");
    }
    return NULL;
}
 
 
 
Converting program args from string to integer.
 
 
Here we assign buffer with arrays of unknown type.
 
 
Here we assign each buffer with his size in bytes.
 
 
Finally we create working threads. The important thing is that they will run simultaneously.
 
 
Waiting until all threads done their job.
 
 
Simple print buffer contents.
 
 
Ok, here is the code.
 
int main(int argc, char **argv) {
    //1
    int bufferSize = atoi(argv[1]);
    int buffersAmount = atoi(argv[2]);

    //2
    buffer = malloc(sizeof(void *)*buffersAmount);

    //3
    int i;
    for (i = 0; i < buffersAmount; ++i) {
        buffer[i] = malloc(bufferSize);
    }

    //4
    i = 0;
    while (i < 2) {
        pthread_create(&tid[i], NULL, &assignBuffer, NULL);
        ++i;
    }

    //5
    for (i = 0; i < 2; i++)
        pthread_join(tid[i], NULL);

    //6
    for (i = 0; i < 4; ++i) {
        printf("%d %s\n", i, (char*)buffer[i]);
    }
    for (i = 0; i < buffersAmount; ++i) {
        free(buffer[i]);
    }
    return 0;
}
 
Feel free to ask if you don't understand something, also sorry for my english it is not my native language.