Arduino Datalogger with Timestamp

#include <SPI.h>
#include <SD.h>
#include <Wire.h>
#include <TimeLib.h>
#include <DS1307RTC.h>
#include <LiquidCrystal_I2C.h>

File myFile;
LiquidCrystal_I2C lcd(0x27, 20, 4);

const char *monthName[12] = {
  "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

tmElements_t tm;

void setup() {
  bool parse = false;
  bool config = false;

  // get the date and time the compiler was run
  if (getDate(__DATE__) && getTime(__TIME__)) {
    parse = true;
    // and configure the RTC with this info
    if (RTC.write(tm)) {
      config = true;
    }
  }

  if (parse && config) {
    Serial.print("DS1307 configured Time=");
    Serial.print(__TIME__);
    Serial.print(", Date=");
    Serial.println(__DATE__);
  } else if (parse) {
    Serial.println("DS1307 Communication Error :-{");
    Serial.println("Please check your circuitry");
  } else {
    Serial.print("Could not parse info from the compiler, Time=\"");
    Serial.print(__TIME__);
    Serial.print("\", Date=\"");
    Serial.print(__DATE__);
    Serial.println("\"");
  }

  Serial.begin(9600);
  lcd.init();
  while (!Serial) ; // wait for serial
  Serial.println("Initializing SD card...");
  if (!SD.begin(4)) {
    Serial.println("initialization failed!");
    while (1);
  }





}

void loop() {
  String data;

  if (RTC.read(tm)) {

    myFile = SD.open("test.txt", FILE_WRITE); // test.txt durch RFID Tag ersetzen FileName = String(RfidTag)+".txt"
    if (myFile) {
      data = checkDigits(tm.Hour) + ":" + checkDigits(tm.Minute) + ":" + checkDigits(tm.Second);
      Serial.println(data);
      myFile.println(data);
      lcd.backlight();
      lcd.clear();
      lcd.print(data);
      myFile.close();
      data = "";
    } else {
      // if the file didn't open, print an error:
      Serial.println("error opening test.txt");
    }
  } else {
    Serial.println("Uhr läuft nicht");
  }
  delay(1000);

  myFile = SD.open("test.txt");
  if (myFile) {
    Serial.println("File opened");
    // read from the file until there's nothing else in it:
    while (myFile.available()) {
      Serial.write(myFile.read());

    }
    // close the file:
    myFile.close();

  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }

}

String checkDigits(int number) {
  String DtZeit;
  DtZeit = String (number);
  if (number >= 0 && number < 10) {
    DtZeit = "0" + String(number);

  }
  return DtZeit;
}

bool getTime(const char *str)
{
  int Hour, Min, Sec;

  if (sscanf(str, "%d:%d:%d", &Hour, &Min, &Sec) != 3) return false;
  tm.Hour = Hour;
  tm.Minute = Min;
  tm.Second = Sec;
  return true;
}

bool getDate(const char *str)
{
  char Month[12];
  int Day, Year;
  uint8_t monthIndex;

  if (sscanf(str, "%s %d %d", Month, &Day, &Year) != 3) return false;
  for (monthIndex = 0; monthIndex < 12; monthIndex++) {
    if (strcmp(Month, monthName[monthIndex]) == 0) break;
  }
  if (monthIndex >= 12) return false;
  tm.Day = Day;
  tm.Month = monthIndex + 1;
  tm.Year = CalendarYrToTm(Year);
  return true;
}