如何从ARM微控制器的GPIO端口读取值？

#include<iostream>
#include <fstream>

int main() {
    // 打开GPIO端口
    std::ofstream gpioExport("/sys/class/gpio/export");
    gpioExport << "4"; // 假设GPIO端口号为4
    gpioExport.close();

    // 设置GPIO端口为输入模式
    std::ofstream gpioDirection("/sys/class/gpio/gpio4/direction");
    gpioDirection << "in";
    gpioDirection.close();

    // 读取GPIO端口的值
    std::ifstream gpioValue("/sys/class/gpio/gpio4/value");
    int value;
    gpioValue >> value;
    gpioValue.close();

    std::cout << "GPIO端口4的值为: "<< value<< std::endl;

    // 取消导出GPIO端口
    std::ofstream gpioUnexport("/sys/class/gpio/unexport");
    gpioUnexport << "4";
    gpioUnexport.close();

    return 0;
}