subtractMonths method

DateTime subtractMonths(
  1. int monthDifference
)

减去月份

Implementation

DateTime subtractMonths(int monthDifference) {
  int yearDiff = monthDifference ~/ 12;
  final int monthDiff = monthDifference % 12;
  int month = this.month - monthDiff;
  if (month < 1) {
    yearDiff = yearDiff - 1;
    month = 12 + month;
  }
  final int year = this.year - yearDiff;
  final int day = this.day + 1;
  return DateTime(year, month, day);
}