this is my method
void mensaje_sms()
{
string numero = "777777"; // this is my variable
SIM900.print("AT+CMGF=1\r");
delay(100);
SIM900.println("AT+CMGS=\"591"numero"\"");
//IM900.println("AT+CMGS=\"59177777777\""); //only in this way does it work
delay(100);
SIM900.println("SEND NUMERO VARIABLE RODO");
delay(100);
SIM900.println((char)26);
delay(100);
SIM900.println();
delay(5000);
Serial.println("SMS sent successfully");
}
how can I send a variable to println?