Weird characters at the end of payload on callback

[dustin-auby]

Hi Guys,

I'm encountering a weird issue with my payloads. im getting extra characters in the payload. mostly a "e" or ".0" will be appended to the end of the payload. in the bellow example i send a air-con mode of "cool" to the topic. in my mqtt client it is received properly as well as home assistant but on my wemos D1 R2 it receives as "coole". any idea what could cause this all of a sudden ?.

i am using pubsubclient v 2.8 any assistance on this would be greatly apriciated

void callback(char* topic, byte* payload, unsigned int length) {

  Serial.print("Message:");
  Serial.println((char*)payload);
}

[knolleary]

You are ignoring the length parameter that tells you how long the payload is.

Instead, your code will print the bytes of payload until it hits a 0x00... so it's pure chance what extra chars youll get.

The quick fix is to do:

payload[length] = 0;

To ensure there is a 0 immediately after the valid bytes of the payload.

[dustin-auby]

Thanks for the quick reply, that has resolved the issue