[Solved] Sort date using lambda expression [closed]

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What you’re ordering by here is the distance between the pivot (the birthdate) and each date. Something like this:

var sorted = data.OrderBy(date => (birthdate - date).TotalDays);

will sort by distance, but put all the after dates first, because the TotalDays will be negative, then the before dates. To avoid that, we need to implement a custom IComparer which compares absolute values, and falls back to the real values in case of equality:

public class AbsoluteComparer : IComparer<double>
{
    public int Compare(double x, double y)
    {
        var absX = Math.Abs(x);
        var absY = Math.Abs(y);

        if (absX > absY)  
            return 1;
        if (absX < absY)
            return -1;

        // If Absolutes are equal, determine by sign.
        if (x > y)
            return 1;
        if (y > x)
            return -1;

        return 0;
    }
}

So the final call would be:

var sorted = data.OrderBy(date => (birthdate - date).TotalDays, new AbsoluteComparer());

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solved Sort date using lambda expression [closed]