problem about serial

Projects Programming
1

HI, I'm trying to send data between two arduino but I've a little problem.
The TX/RX modules are rf 443MHz. the TX print via serial two message "X1234" and "X4321"
The rx module read the buffer but when I try to put an IF there's a problem:

#include <SoftwareSerial.h>

int  car[3] ;
int carattere;

void setup(){
Serial.begin(2400);

}


void loop(){
  riprova:
  for (int i = 0; i < 4; i++) {
      car[i] = 0;
  }
  if (Serial.available()){
    if (char(Serial.read()) != 'X'){
        goto riprova;
    }

if (char(Serial.read()) != '1'){
        goto riprova;
    }
    car[0] = Serial.read(); // Then: Get them. 
    car[1] = Serial.read(); // Then: Get them. 
    car[2] = Serial.read(); // Then: Get them. 
    Serial.print(char(car[0]));
    Serial.print(char(car[1]));
    Serial.println(char(car[2]));
    }
  }

If I delete the second IF it's ok but with do nothing....
Any suggestion??.
Many thanks

2

goto's are rarely needed in C.
Try using "while" or "do..while" constructs.

You have three consecutive "Serial.read"s, but no guarantee that there is data for them to read.

 for (int i = 0; i < 4; i++)

"car" is only declared with three elements.

3

AWOL:
goto's are rarely needed in C.
Try using "while" or "do..while" constructs.

I understand this, but Isn't the problem... the goto it's ok...

AWOL:
You have three consecutive "Serial.read"s, but no guarantee that there is data for them to read.

ok, but if I delete the second IF it's ok... I've tryed also this

if (char(var) == 'X' && char(var) =='1')

:
but same result... nothing..
thank you

4 
void loop()
{
  for (int i = 0; i < 3; i++) {
      car[i] = 0;
  }

  do {
   while (Serial.available() == 0);
  } while (Serial.read()) != 'X');

  for (int i = 0; i < 3; ++i) {
    while (Serial.available() == 0);
    car[i] = Serial.read();
  }
  Serial.print(char(car[0]));
  Serial.print(char(car[1]));
  Serial.println(char(car[2]));
}