How to use libudev in Linux to get USB device VID and PID

#include <libudev.h>
#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
#include <unistd.h>

int main (void)
{
  struct udev *udev;
  struct udev_enumerate *enumerate;
  struct udev_list_entry *devices, *dev_list_entry;
  struct udev_device *dev;

  /* Create the udev object */
  udev = udev_new();
  if (!udev) {
    printf("Can't create udev\n");
    exit(1);
  }

  /* Create a list of the devices in the 'hidraw' subsystem. */
  enumerate = udev_enumerate_new(udev);
  udev_enumerate_add_match_subsystem(enumerate, "hidraw");
  udev_enumerate_scan_devices(enumerate);
  devices = udev_enumerate_get_list_entry(enumerate);
  /* For each item enumerated, print out its information.
    udev_list_entry_foreach is a macro which expands to
    a loop. The loop will be executed for each member in
    devices, setting dev_list_entry to a list entry
    which contains the device's path in /sys. */
  udev_list_entry_foreach(dev_list_entry, devices) {
    const char *path;

    /* Get the filename of the /sys entry for the device
      and create a udev_device object (dev) representing it */
    path = udev_list_entry_get_name(dev_list_entry);
    dev = udev_device_new_from_syspath(udev, path);

    /* usb_device_get_devnode() returns the path to the device node
      itself in /dev. */
    printf("Device Node Path: %s\n", udev_device_get_devnode(dev));

    /* The device pointed to by dev contains information about
      the hidraw device. In order to get information about the
      USB device, get the parent device with the
      subsystem/devtype pair of "usb"/"usb_device". This will
      be several levels up the tree, but the function will find
      it.*/
    dev = udev_device_get_parent_with_subsystem_devtype(
         dev,
         "USB",
         "usb_device");
    if (!dev) {
      printf("Unable to find parent usb device.");
      exit(1);
    }

    /* From here, we can call get_sysattr_value() for each file
      in the device's /sys entry. The strings passed into these
      functions (idProduct, idVendor, serial, etc.) correspond
      directly to the files in the directory which represents
      the USB device. Note that USB strings are Unicode, UCS2
      encoded, but the strings returned from
      udev_device_get_sysattr_value() are UTF-8 encoded. */
    printf(" VID/PID: %s %s\n",
        udev_device_get_sysattr_value(dev,"idVendor"),
        udev_device_get_sysattr_value(dev, "idProduct"));
    printf(" %s\n %s\n",
        udev_device_get_sysattr_value(dev,"manufacturer"),
        udev_device_get_sysattr_value(dev,"product"));
    printf(" serial: %s\n",
        udev_device_get_sysattr_value(dev, "serial"));
    udev_device_unref(dev);
  }
  /* Free the enumerator object */
  udev_enumerate_unref(enumerate);

  udev_unref(udev);

  return 0;
}