bring multi extension files and stop looping them when the list reach the end - c#

Question

i have a simple software that loop multi Images/videos
and show them one by one using (Next)-(previous) buttons

so far i success bring only one extension in a time using :

string[] FileList = Directory.GetFiles(Dir, "*.jpg", SearchOption.AllDirectories);

and i tried stop looping when the list reach the End by using this code :

int currentPosition = 0;
if (currentPosition != ImageList.Length) currentPosition++;

excuse my mistakes cause i still Noob in c# but when I debug its says
> IndexOutOfRangeException

and after i add multi Extensions like this :

    string[] VOut_AVI = Directory.GetFiles(@Curr_DirectoryName, "*.avi", SearchOption.AllDirectories);
    string[] VOut_MP4 = Directory.GetFiles(@Curr_DirectoryName, "*.mp4", SearchOption.AllDirectories);
    string AddMP4 = VOut_MP4[VOut_MP4.Length - 1];
    //------ Adding other format to our call ------------
    Array.Resize(ref VOut_AVI, VOut_AVI.Length + 1);
    VOut_AVI[VOut_AVI.Length - 1] = AddMP4;

    // just for test ----->>
    MessageBox.Show("Video link : " + VOut_AVI[currentPosition]);

i get this error said (XamlParserException) for that one .

if you know easy way to get multi extensions without using that much of coding like i did i'll be happy to know it also my looping process as you saw not that good if you can guide me to the right way , i'm still learning those things its a bit hard for me cause i come from a completely different environment , thanks in advance

Answer 1

To get a list of filenames with different extensions use Directory.EnumerateFiles and concat these queries.

IEnumerable<string> myFilesQuery = new string[] { };

myFilesQuery = myFilesQuery.Concat( Directory.EnumerateFiles( dir, "*.avi", SearchOption.AllDirectories ) );
myFilesQuery = myFilesQuery.Concat( Directory.EnumerateFiles( dir, "*.mp4", SearchOption.AllDirectories ) );
myFilesQuery = myFilesQuery.Concat( Directory.EnumerateFiles( dir, "*.jpg", SearchOption.AllDirectories ) );

// nothing will happen until we call

IList<string> myFiles = myFilesQuery.ToList( );

If you like to have a one-line-of-code for your code, write a helper like

public static class DirectoryHelper
{
    public static IEnumerable<string> EnumerateFiles( 
        string path, 
        SearchOption searchOption, 
        params string[] searchPatterns )
    {
        if ( searchPatterns == null )
            throw new ArgumentNullException( nameof( searchPatterns ) );

        IEnumerable<string> result = new string[] { };

        foreach ( var searchPattern in searchPatterns )
        {
            result = result.Concat( Directory.EnumerateFiles( path, searchPattern, searchOption ) );
        }

        return result;
    }
}

and inside our code you have only

IList<string> myFiles 
    = DirectoryHelper
        .EnumerateFiles( 
            dir, 
            SearchOption.AllDirectories, 
            "*.avi", "*.mp4", "*.jpg" )
        .ToList();

You do not have to worry about any length of an array. The list will have the number of containing elements in the Count property.

All collections are are zero-based and the first item has index 0 and the last item has index Count-1 (collection) or Length-1 (array). You reach the end when currentPosition >= mylist.Count-1 and you can increase the index as long as currentPosition < mylist.Count-1.

Update

There is already an answer here on SO dealing with multiple search patterns with a parallel implementation

https://stackoverflow.com/a/3754470/1744164