How can I count weekdays only when I am choosing two dates using DirectoryInfo().GetFiles?

Question

I am trying to find a function to use with the DirectoryInfo().GetFiles function to only count weekdays when I am looking for files in a date range.

The only function I found is

.Count(x => x.DayOfWeek != DayOfWeek.Saturday && x.DayOfWeek != DayOfWeek.Sunday);

which is incompatible with fileInfos.Where

DateTime d1 = DateTime.Now;
d2 = d1.AddDays(FileAgeYounger);
DateTime d3 = DateTime.Now;
d4 = d3.AddDays(FileAgeOlder);

if (subfolders == true & 
    FileExtension != null & 
    Fileprefix != null & 
    FileUseRelativeAgeOlder == true & 
    FileUseRelativeAgeYounger == false & CountWeekDays == true)
{
    FileInfo[] fileInfos = new DirectoryInfo(FolderLocation).GetFiles("*.*", SearchOption.AllDirectories);
    IEnumerable<FileInfo> files = fileInfos.Where((f) => f.Extension.Equals(FileExtension)
                                                      && f.Name.StartsWith(Fileprefix)
                                                      && f.CreationTime >= d3
                                                      && f.CreationTime <= d4);
}                        

Answer 1

In this code...

.Count(x => x.DayOfWeek != DayOfWeek.Saturday && x.DayOfWeek != DayOfWeek.Sunday);

...x is a FileInfo, which doesn't have a DayOfWeek property. Instead, you need to use whichever of the three *Time properties of FileInfo is appropriate; looking at the condition you passed to .Where() that appears to be CreationTime...

int count = files.Count(x => x.CreationTime.DayOfWeek != DayOfWeek.Saturday && x.CreationTime.DayOfWeek != DayOfWeek.Sunday);

Alternatively, that code could be made to work by using .Select() to retrieve just the desired *Time property...

int count = files
    .Select(f => f.CreationTime)
    .Count(x => x.DayOfWeek != DayOfWeek.Saturday && x.DayOfWeek != DayOfWeek.Sunday);

In this case, x is a DateTime.

Also, keep in mind the differences between the older GetFiles() method and the newer EnumerateFiles() method...

The EnumerateFiles and GetFiles methods differ as follows:

• When you use EnumerateFiles, you can start enumerating the collection of FileInfo objects before the whole collection is returned.
• When you use GetFiles, you must wait for the whole array of FileInfo objects to be returned before you can access the array.

Therefore, when you are working with many files and directories, EnumerateFiles can be more efficient.

EnumerateFiles() is well-suited for this kind of filesystem search/filtering, and, I think, generally the preferred method to use.