test.c

来自「2.6内核做简单的字符驱动的例子」· C语言 代码 · 共 59 行

#include <sys/types.h>

#include <sys/stat.h>

#include <stdio.h>

#include <fcntl.h>

 

main()

{

    int fd, num;

    fd=open("/dev/globalvar", O_RDWR, S_IRUSR|S_IWUSR);     //可读写方式打开设备文件

    if(fd!=-1)

    {

        read(fd, &num, sizeof(int));                        //读取设备变量

        printf("The globalvar is %d\n", num);

 

        printf("Please input the num written to globalvar\n");

        scanf("%d", &num);

        write(fd, &num, sizeof(int));                       //写设备变量

 

        read(fd, &num, sizeof(int));                        //再次读取刚才写的值

        printf("The globalvar is %d\n", num);

 

        close(fd);                                          //关闭设备文件

    }

    else

    {

        printf("Device open failure\n");

    }

}