I have a function to decrement a date by one day each time is called.

private IEnumerable<DateTime> EachDay(DateTime from, DateTime thru)
{
    for (var day = thru.Date; day.Date >= from.Date; day = day.Subtract(TimeSpan.FromDays(1)))//day.AddDays(-1))
    {
        yield return day;
    }
}

Seems to work fine until i arrive to the previous month. If someone have a solution ?

CodePudding user response：

I would be using something like this

private IEnumerable<DateTime> EachDay(DateTime from, DateTime thru)
{
    var days=(thru.Date - from.Date).Days;
    if (days <= 0)  yield return DateTime.MinValue;
    else for (var day = days; day >= 0; day-=1)
    yield return from.Date.AddDays(day);
}

test

var thru =new DateTime(day: 01,month:12, year:2021); 
var from= thru.AddDays(-10);
EachDay(from,thru).Dump();

result

    2021-12-01
    2021-11-30
    2021-11-29
    2021-11-28
    2021-11-27
    2021-11-26
    2021-11-25
    2021-11-24
    2021-11-23
    2021-11-22
    2021-11-21

CodePudding user response：

To some extent you're reinventing a wheel here. You can use Enumerable.Range to do your dates:

var f = DateTime.Now;
var t = DateTime.Now.AddDays(-45);
    
var d = Enumerable.Range(0, (int)((f-t).TotalDays)).Select(x => f.AddDays(-x));   
    

The dates in d have no problem crossing a month boundary