MQTT, ESP8266, Analogwrite, Nodered

Im a bit stuck with my project and hope you guys can point me in the right direction.

Im using node red on a rpi to communicate with an ESP8266. I have a dashboard in node red with a slider. The slider (is supposed to) control an LED via PWM signal.

So far I have managed to come up (more or less copy paste -.-) with a code that allows me to use a switch to turn on/off the LED.

 void callback(String topic, byte* message, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.print(". Message: ");
  String messageTemp;
  for (int i = 0; i < length; i++) {
    messageTemp += (char)message[i];
      Serial.print("Changing Room lamp to ");
      if(messageTemp == "on"){
        digitalWrite(lamp, HIGH);
      else if(messageTemp == "off"){
        digitalWrite(lamp, LOW);

this works..

What I want to do now is use the analogwrite function. So I recieve a MQTT mesage with a value between 0-255. This part already works.

Where I am stuck is, I dont know how to store the mqtt message I recieve inside an int or something so that I can do something like analogwrite(lamp, value_from_mqtt)...

I don't see a reason for the messageTemp variable. It just wastes memory. If you use the strncmp() function you can check the content of the message variable directly.

To parse a number string you can use the atoi() function.

As you have the message in the messageTemp string you could use the toInt() method to convert it to an integer.