TX2 gpio c++ ros读取通过文件方式读取

cd /sys/class/gpio/
echo 388 > export #使能端口
cd gpio388
cat direction #方向
cat value #输出值

#include 
#include 

using namespace std;
int main(int argc,char** argv)
{
       ifstream dirStream("/sys/devices/c2f0000.gpio/gpiochip1/gpio/gpio338/value");
       if(!dirStream)
       {
         cout<<"unable open"<>value_;
       cout< 
4.ros执行
 
#include "ros/ros.h"
#include "std_msgs/Int8.h"
#include "sstream"
#include 
#include 

using namespace std;
int main(int argc,char** argv)
{
       ros::init(argc,argv,"gpio_ss");
       ros::NodeHandle n;
       ros::Publisher pub=n.advertise("gpio_ss",100);
       ros::Rate loop_rate(1);
       std_msgs::Int8 msg;
       int ss=0;
       while(ros::ok())
       {
          ifstream dirStream("/sys/devices/c2f0000.gpio/gpiochip1/gpio/gpio338/value");
          if(!dirStream)
          {
            cout<<"unable open"<>ss;
	  msg.data=ss;
          cout<