This line of C# code calculates the date of "last...

This line of C# code calculates the date of "last Friday" relative to a specific given date, represented by the variable lastDay.

Here's a breakdown of what it does:

1. lastDay: This is the base date or the given date you are working with (likely a DateTime object).

2. lastDay.DayOfWeek: Retrieves the day of the week for the lastDay (e.g., Sunday = 0, Monday = 1, ..., Saturday = 6).

3. (int)lastDay.DayOfWeek: Converts the DayOfWeek enumeration to its corresponding integer value.

4. lastDay.AddDays(-(int)lastDay.DayOfWeek): Subtracts the numeric value of the DayOfWeek from lastDay. This effectively adjusts lastDay backward to the previous Sunday. (By subtracting the numeric representation of the day, it calculates how far to go back to hit Sunday.)

5. Assigns this calculated date to the variable lastFriday.

   If lastFriday is specifically intended to find "last Friday," we assume there is additional context ensuring that lastDay is already adjusted or specified correctly. Otherwise, further adjustment may be needed, e.g., reducing days further to pinpoint the previous Friday.

TL;DR:

The code calculates the previous Sunday (depending on what lastDay is). If the goal is explicitly to find "last Friday," this line of code alone may fall short unless lastDay already represents a specific date close to Friday.