How do you format the day of the month to say “11th”, “21st” or “23rd” in Dart?

Question

I have a date and want to display the date with the suffix th, st, rd, etc.

Here is my dart code.

int year = date.year;
int month = date.month;
int day = date.day;

DateTime dateSelected = new DateTime(year, month, day);
var formatter = new DateFormat('EEEE MMMM dd, yyyy');
displayDate = formatter.format(dateSelected);

This displays dates as "Wednesday April 23, 2014" for example, but I need "Wednesday April 23rd, 2014".

I'm using the intl package.

import 'package:intl/intl.dart';

Answer 1

String getDayOfMonthSuffix(int dayNum) {
    if(!(dayNum >= 1 && dayNum <= 31)) {
      throw Exception('Invalid day of month');
    }

    if(dayNum >= 11 && dayNum <= 13) {
      return 'th';
    }

    switch(dayNum % 10) {
      case 1: return 'st';
      case 2: return 'nd';
      case 3: return 'rd';
      default: return 'th';
    }
}

The above method gets the suffix for you. You can use string concatenation or string interpolation to put together the format you want. e.g

'$day ${getDayOfMonthSuffix(day)}'

Answer 2

May not be better...but shorter

static final _dayMap = {1: 'st', 2: 'nd', 3: 'rd'};
static String dayOfMonth(int day) => "$day${_dayMap[day] ?? 'th'}";