char* text;
char* number;
bool error;                     //to catch the response of sendSms


void setup(){
   GSM.begin(4800);
   text="Testing Sms";          //text for the message.
   number="2926451386";         //change to a valid number.
   error=SIM800L .sendSms(number,text);
}

#include <Sim800L.h>
#include <SoftwareSerial.h>
#include <UIPEthernet.h>

#define RX  10
#define TX  11

Sim800L GSM(RX, TX);

int buzzer = 8;
int smokeA0 = A5;
int smokeA1 = A4;
int smokeA2 = A3;

int sensorThres1 = 650;
int sensorThres2 = 500;
int sensorThres3 = 500;


byte mac[6] = {0x54, 0x55, 0x58, 0x10, 0x00, 0x24};
EthernetClient client;
char server[] = "192.168.2.100";
int  interval = 5000;
char uid[] = "1";
String response = String(100);
char* text;
char* number;

void setup() {

  pinMode(buzzer, OUTPUT);
  pinMode(smokeA0, INPUT);
  pinMode(smokeA1, INPUT);
  pinMode(smokeA2, INPUT);


  Serial.begin(9600);
  Ethernet.begin(mac);

  Serial.print("IP Address        : ");
  Serial.println(Ethernet.localIP());
  GSM.begin(4800);
}

void loop() {
   int analogSensor1 = analogRead(smokeA0);
   int analogSensor2 = analogRead(smokeA1);
   int analogSensor3 = analogRead(smokeA2);


  if (analogSensor1 > sensorThres1 || analogSensor2 > sensorThres2 || analogSensor3 > sensorThres3){

if(client.connect(server, 80)){
        Serial.println("-> Connected");
        // Make a HTTP request:
        client.print( "GET /apartment/insert.php?");
        client.print("uid=");
        client.print(uid);
        client.println( " HTTP/1.1");
        client.print( "Host: " );
        client.println(server);
        client.println( "Connection: close" );
        client.println();
        client.println();

       while (client.connected()) {
          if (client.available()) {
            char c = client.read();
            //Serial.print(c);
            response= response + c;
          }
       }

       int contentBodyIndex = response.lastIndexOf('n');
       if (contentBodyIndex > 0) {
          number = response.substring(contentBodyIndex); // THE ERROR POINTS TO THIS LINE OF CODE
          Serial.print(number);
          text = "Smoke was detected in your apartment unit";
          Sim800L.sendSms(number,text);
       }



        client.stop();
        delay(1000);
        tone(buzzer, 1000);
        delay(10000);
        noTone(buzzer);
        delay(1000);
      }else{
        Serial.println("--> connection failed/n");
      }
 }
 else
 {
   noTone(buzzer);
 }
 delay(1000);
}