Issue with converting String to unsigned long

Question

I have a little problem with converting a char string array to an unsigned long. This is my input for executeCommand().

0001000118218;326

And this is what i get back.

Received command: 0001000118218;326

transmit code: 1821

transmit period: 32

I don't understand why the last digit is dropped...

#define id_length 4
#define command_length 4
const String my_id = "0001";
//Command execution methods
void executeCommand(String inputData) {
  if(!my_id.equals(inputData.substring(0, id_length))) {
    return;
  }

  Serial.print("Received command: ");
  Serial.println(inputData);
  String command = inputData.substring(id_length, id_length + command_length);
  String parameters = inputData.substring(id_length + command_length);


  for (int i = 0; i < 3; i++) {
  if(command == "0001") {    //RF power command
    unsigned long rfid_long;
    unsigned long periodid_long;
    char rfid[parameters.indexOf(';')];
    char periodid[3];
    parameters.substring(0, parameters.indexOf(';')).toCharArray(rfid, parameters.indexOf(';'));
    parameters.substring(parameters.indexOf(';') + 1).toCharArray(periodid, 3);
    rfid_long = strtoul(rfid, NULL, 10);
    periodid_long = strtoul(periodid, NULL, 10);
    sendRF(rfid_long, periodid_long);
  }
  else {
    Serial.println("Unknown command received");
  }
  delay(10);
  }
}

void sendRF(unsigned long transmitCode, unsigned int transmitPeriod) {
 //digitalWrite(transmitLedPin, HIGH);
 Serial.print("transmit code: ");
 Serial.println(transmitCode);
 Serial.print("transmit period: ");
 Serial.println(transmitPeriod);
 RemoteSwitch::sendTelegram(generateTelegram(transmitCode, transmitPeriod), rfSubmitPin);
 //digitalWrite(transmitLedPin, LOW);
}

Answer 1

char periodid[3];

Should be char periodid[4] if you want to have a string of length 3 in it; 3 elements for the contents and 1 for the zero terminator.

You'll also have to change toCharArray(periodid, 3); to toCharArray(periodid, 4); or better, toCharArray(periodid, sizeof(periodid));

Answer 2

What if you convert command to a character array and use strchr?

char* separator = strchr(command, ';');
if (separator == NULL) return;

char* rfid = command + id_length;
char* periodid = separator + 1;

unsigned long rfid_long = strtoul(rfid, &separator, 10);
unsigned long periodid_long = strtoul(periodid, NULL, 10);