Working with strings and functions

Projects Programming
1

Hi to everybody,
I am quite new to arduino and need some help with a function.

i have this function:

void sendSms(String smsNumber, String smsText)
{
  Serial.println("\n--- SEND SMS START ---");
  digitalWrite(LED_BUILTIN, HIGH);

  myGsm.write("AT+CMGF=1\r");
  waitSerial("OK");

  myGsm.write("AT+CMGS="+smsNumber+"\r");
  waitSerial(">");  

  myGsm.write(smsText);
  myGsm.write(0x1A);
  waitSerial("OK");  

  Serial.println("--- SEND SMS END ---");
  digitalWrite(LED_BUILTIN, LOW);
}

from another function want to use the above as sendSms("to number", "with sms text this");

can not do that, getting many errors.

First of all how do i join strings as this "AT+CMGS="+smsNumber+"\r" is wrong!

Also why Serial.Write() works ok if i put a string e.g. Serial.Write("some text"); but not if i try to use a String variable e.g. myGsm.write(smsText);

What am i doing wrong?

Thank you all in advance.

2

It is not a good idea to use the String (capital S) class on an Arduino as it can cause memory corruption in the small memory on an Arduino. Just use cstrings - char arrays terminated with 0.

To be honest, if that was my project I would create a global char array to hold the message and then it would be directly accessible from the function.

...R

3

Thank you Robin2 for your comments, solved my problem with Serial.print(), just found out that the write() functions sends bytes and that was my problem.

Thank you again.