linux 文件指针

#include <stdio.h>

int main() {
    FILE *file = fopen("example.txt", "r+");
    if (file == NULL) {
        perror("Error opening file");
        return 1;
    }

    // 定位到文件的特定位置
    fseek(file, 10, SEEK_SET);

    // 读取或写入数据
    char data = fgetc(file);
    printf("Data at position 10: %c\n", data);

    // 关闭文件
    fclose(file);
    return 0;
}

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

FILE *file;
pthread_mutex_t mutex;

void *thread_func(void *arg) {
    pthread_mutex_lock(&mutex);
    // 执行文件操作
    fseek(file, 0, SEEK_SET);
    fputc('A', file);
    pthread_mutex_unlock(&mutex);
    return NULL;
}

int main() {
    file = fopen("example.txt", "w+");
    if (file == NULL) {
        perror("Error opening file");
        return 1;
    }

    pthread_mutex_init(&mutex, NULL);

    pthread_t threads[2];
    for (int i = 0; i < 2; ++i) {
        pthread_create(&threads[i], NULL, thread_func, NULL);
    }

    for (int i = 0; i < 2; ++i) {
        pthread_join(threads[i], NULL);
    }

    fclose(file);
    pthread_mutex_destroy(&mutex);
    return 0;
}