SoftwareSerial + Serial.printlen() not working properly

Question

I want to read a SMS message , find it's length and do some "substring();" operation on received SMS. My last two(2) statements do not work . How can I get correct answers? What are correct codes ?

#include <SoftwareSerial.h>
#include <string.h> 
#include <ctype.h>
SoftwareSerial mySerial(2,3);
String TelephoneNumberText="";
void setup()
{
 pinMode(13, OUTPUT); 
 digitalWrite(13, LOW); 
 mySerial.begin(9600); 
 Serial.begin(9600); 
 delay(100); 
 mySerial.println("AT+CMGF=1\r"); //Sets the GSM Module in Text Mode 
 delay(500); 
}
void loop() 
{
 while(mySerial.available())
 {
 char s;
 s = mySerial.read(); 
 TelephoneNumberText = TelephoneNumberText + s; 
 } 
 Serial.println(TelephoneNumberText); // this statement works
 Serial.println(TelephoneNumberText.length()); // this statement dose not works
 Serial.println(TelephoneNumberText.substring(0,3));// this statement dose not works
} // end loop

• muditha: Serial.println(TelephoneNumberText); // this statement works Serial.println(TelephoneNumberText.length()); // this statement dose not works Serial.println(TelephoneNumberText.substring(0,3));// this statement dose not works /* please tell me correct codes for above two(2) statements */

Answer 1

Are you sure a string like this can be used?

Better anyway to not each time let a dynamic string be created, but use a fixed string e.g.

char TelephoneNumberText[16]; 

Set the length of the max number, and change other string functions accordingly.