std_msgs::string compare in a callback cpp node

edit

Hi all,

I'm trying to create a node with rosserial on Arduino. It should publish some sensor information and acts when I publish a command through a command topic. I wrote a cpp node with a callback function:

void commandsCB (const std_msgs::String& commands)
{
  nh.loginfo("Reciving new message... \n");
  nh.loginfo(commands.data);
  nh.loginfo(scan.data);
  if (commands.data == scan.data)
  {
    scanning(pos, flag, minAngle, maxAngle, myservo, servoPos, pub_pos, scansNum, range_msg, pub_range);
    nh.loginfo("Scanning...");
  }
  if (commands.data == forward.data)
  {
    cart.forwardDrive();
    getRange(range_msg, pub_range);
    nh.loginfo("Driving forward...");
  }
  if (commands.data == backward.data)
  {
    cart.backwardDrive();
    getRange(range_msg, pub_range);
    nh.loginfo("Driving backward...");
  }
  if (commands.data == rightTurn.data)
  {
    cart.rightTurn();
    getRange(range_msg, pub_range);
    nh.loginfo("Turning right...");
  }
  if (commands.data == leftTurn.data)
  {
    cart.leftTurn();
    getRange(range_msg, pub_range);
    nh.loginfo("Turning left...");
  }
}

ros::Subscriber<std_msgs::String> sub_commands ("/commands", &commandsCB);

Where scan.data, forward.data etc all std_msgs::String types.

When I try this node and publish command, for example,

scan

, I get from both

nh.loginfo(commands.data)

and

nh.loginfo(scan.data)

"scan", but it doesn't go into the if condition in the following lines in the callback.

I wonder if that's the right way to write this callback.

I'll appreciate any help, Thanks in advance, Iftach.