写一个linux系统下的c代码片段，功能为创建两个线程，分别对公共资源进行读写，线程A读取值，线程B写入值，两个线程通过linux读写锁pthread_rwlock_t进行互斥

在Linux系统下，使用C语言编写一个简单的线程示例，我们将创建两个线程，线程A负责读取公共资源，线程B负责写入。这里我们使用`pthread_rwlock_t`（读写锁）来进行互斥访问：

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

#define MAX_VALUE 100
int shared_value = 0;
pthread_rwlock_t read_write_lock;

void *thread_reader(void *arg) {
    int i;
    pthread_rwlock_rdlock(&read_write_lock);
    for (i = 0; i < MAX_VALUE; ++i) {
        printf("Thread A reading: %d\n", shared_value);
        // 模拟读取操作，实际应用中此处应替换为真实的读操作
        sleep(1); // 稳定演示
    }
    pthread_rwlock_unlock(&read_write_lock);
    return NULL;
}

void *thread_writer(void *arg) {
    int i;
    for (i = 0; i < MAX_VALUE; ++i) {
        pthread_rwlock_wrlock(&read_write_lock);
        shared_value += 1;
        printf("Thread B writing: %d\n", shared_value);
        pthread_rwlock_unlock(&read_write_lock);
        sleep(1); // 稳定演示
    }
    return NULL;
}

int main() {
    pthread_t reader_thread, writer_thread;

    if (pthread_rwlock_init(&read_write_lock, NULL) != 0) {
        perror("Failed to initialize read-write lock");
        exit(EXIT_FAILURE);
    }

    pthread_create(&reader_thread, NULL, thread_reader, NULL);
    pthread_create(&writer_thread, NULL, thread_writer, NULL);

    pthread_join(reader_thread, NULL);
    pthread_join(writer_thread, NULL);

    pthread_rwlock_destroy(&read_write_lock);
    printf("Shared value after threads finish: %d\n", shared_value);
    return 0;
}