You can do this way.
Namespace
C#
using System.Linq;
VB.Net
Imports System.Linq
Code
C#
string[] files = Directory.GetFiles(ImageUploadPath).Where(f => f.EndsWith("png")).ToArray();
foreach (string file in files)
{
}
VB.Net
Dim files As String() = Directory.GetFiles(ImageUploadPath).Where(Function(f) f.EndsWith("png")).ToArray()
For Each file As String In files
Next