flutter _ 날짜 사용법(DateTime, Duration, difference, isAfter, isBefore, add, substract)

void main() {
  DateTime now = DateTime.now(); // 현재 날짜시간
  
  print(now); // 2023-01-01 20:17:51.546
  print(now.year); // 2023
  //년, 월, 일, 시, 분, 초, 밀리
  
  Duration duration = Duration(seconds: 60); // 기간을 나타냄
  
  print(duration); // 0:01:00.000000
  print(duration.inDays); // 0
  print(duration.inHours); // 0
  print(duration.inMinutes); // 1
  print(duration.inSeconds); // 60
  print(duration.inMilliseconds); // 60000
  
  DateTime specificDay = DateTime(
    2022 // 년도는 필수, 나머진 옵션
  );
  print(specificDay); // 2022-01-01 00:00:00.000
  
  final difference = now.difference(specificDay); // 두 날짜를 비교할 수 있음
  
  print(difference); // 8780:17:51.546000
  print(difference.inDays); // 365
  
  print(now.isAfter(specificDay)); // true
  print(now.isBefore(specificDay)); // false
  
  
  print(now.add(Duration(hours: 10))); // 2023-01-02 06:17:51.546
  print(now.subtract(Duration(seconds: 500))); // 2023-01-01 20:09:31.546
}