sort string array due to DayOfWeek

Question

I have an string array

string[] days={ "1", "2", "6" }

I want to sort it according to DayOfWeek increasingly. For example "1" is Monday, "2" is Tuesday,"6"is saturday. Today is Thursday. So nearest one is Saturday,Monday,Tuesday. So final array will be

days={ "6", "1", "2" }

I couln't find any solution to sort them . How can I sort them.

Thanks in advance.

How these are nearest one `Saturday,Monday,Tuesday.` of `Thursday`? What logic behind your **nearest one**? — er-sho, Mar 14 '19 at 12:36
I mean nearest day of today It will be sorted corresponfing to today Saturday is nearest day to today. Monday comes later, Tuesday comes later.@er-sho — mr. pc_coder, Mar 14 '19 at 12:38

RoadRunner · Answer 1 · 2019-03-14T13:19:06.193

You can use LINQ for this:

string[] days = { "1", "2", "6" };

var today = (int)(DateTime.Now.DayOfWeek + 6) % 7;

var result = days
    .GroupBy(x => int.Parse(x) > today)
    .OrderByDescending(x => x.Key)
    .SelectMany(g => g.OrderBy(x => x));

Console.WriteLine("[{0}]", string.Join(", ", result));
# [6, 1, 2]

Which does the following:

Splits the before and after days into two groups
Sorts(descending) the after days before the before days
Sorts(ascending) each group

shingo · Accepted Answer · 2019-03-14T12:49:51.170

1

String is a bit complex to explain, so I use int instead.

Let the day-of-week always not smaller than today, then compare.

int[] days = { 1, 2, 6 };
int today;
Array.Sort(days, (d1, d2) =>
{
    if(d1 < today)
       d1 += 7;
    if(d2 < today)
       d2 += 7;
    return d1.CompareTo(d2);
});

Short form

Array.Sort(days, (d1, d2) => (d1 < today ? d1 + 7 : d1).CompareTo(d2 < today ? d2 + 7 : d2));

https://dotnetfiddle.net/QsVnIr

edited Mar 14 '19 at 12:49

answered Mar 14 '19 at 12:43

shingo

18,436
5
23
42

So, using `int.Parse` to get `int` out of `string` makes it complex how? – Rand Random Mar 14 '19 at 13:00
Do you see the adverb `a bit` ? – shingo Mar 14 '19 at 13:05
Nope, all I see is a bit strange excuse for not calling `int.Parse`, and as you may see all other given answer use `int.Parse` - your statement is a bit odd. – Rand Random Mar 14 '19 at 13:40

score 1 · Answer 3 · answered Mar 14 '19 at 13:21

I don't know if you want in-place sorting or not, but in case you don't want to change your array (or chain more processing to the array), then you can use LINQ to sort the array

var today = (int)DayOfWeek.Thursday;
int weekDays = 7;
string[] days = { "1", "2", "6" };
var sortedDays = days.Select(int.Parse).OrderBy(d => d > today ? d - today : d + weekDays - today);

You can use a similar logic in the Array.Sort method too, if you wish to go that route

sort string array due to DayOfWeek

3 Answers3