strcmp script reading serial monitor failing

Question

I have a script reading the serial monitor and looking for an "OK" response. I am able to capture the OK response in a variable named message and print it to the serial monitor, but when I attempt to use the message variable in an if statement it is not performing as expected. When the variable message = OK the statement below is still giving a false. Does anyone know where the issue might be?

 if (strcmp (message,"OK") == 0) {
  Serial.println("true");
 }
 else {
  Serial.println("false");
 }

The complete code:

//#include <HardwareSerial.h>
const unsigned int MAX_MESSAGE_LENGTH = 12;

void setup() {
Serial2.begin(115200,SERIAL_8N1); //open modem serial port
Serial.println("serial ports are open");
}

void loop() {
  
 Serial2.write("AT\r\n");

 while (Serial2.available() > 0){
   //Create a place to hold the incoming message
   static char message[MAX_MESSAGE_LENGTH];
   static unsigned int message_pos = 0;
   
   //Read the next available byte in the serial receive buffer
   char inByte = Serial2.read();
   
   //Message coming in (check not terminating character) and guard for over message size
   if ( inByte != '\n' && (message_pos < MAX_MESSAGE_LENGTH - 1) )
   {
     //Add the incoming byte to our message
     message[message_pos] = inByte;
     message_pos++;
   }
   
   //Full message received...
   else
   {
     //Add null character to string
     message[message_pos] = '\0';
        //Print the message (or do other things)
     Serial.println("loop");
     delay(100);
     Serial.println(message);
     //Reset for the next message
      message_pos = 0;
     
     if (strcmp (message,"OK") == 0) {
      Serial.println("true");
     }
     else {
      Serial.println("false");
     }
   }
      
 }
delay(5000);
}

Serial monitor looks like this:

22:11:51.970 -> serial ports are open
22:12:16.984 -> loop
22:12:17.078 -> AT


22:12:17.078 -> false
22:12:17.078 -> loop
22:12:17.171 -> OK

22:12:17.171 -> false
22:12:17.171 -> loop
22:12:17.266 -> AT


22:12:17.266 -> false
22:12:17.266 -> loop
22:12:17.360 -> OK

22:12:17.360 -> false

Answer 1

The received response is "OK\r\n", so the actual message is "OK\r". It helps for debugging if you temporarily print each received character.

To ignore the echo of the command, insert another strcmp() for it and react accordingly, for example do nothing.