C# LINQ Orderby - How does true/false affect orderby?

The OrderBy method will sort items in ascending order by default. Now, given that the numeric representation of a boolean is:

• false = 0
• true = 1

false values will naturally come first. If you want to reverse the order just use the descending keyword:

var trueData = (from data in x
               orderby numbersToFilterBy.Contains(data.Id) descending, data.Id
                select data).ToList();

Basically, false is earlier than true... think of them as false=0, true=1. This is in-keeping with the documentation for bool.CompareTo(bool).

If you want to prioritize "true" values to the start, just use OrderByDescending instead.

Ordering isn't about priority – it's about ordinal value. You're doing an ascending order against a boolean value, and false has a lower ordinal value than true in that context.