c# get folder path from file path

string filename = @"C:/folder1/folder2/file.txt";
string FolderName = new DirectoryInfo(System.IO.Path.GetDirectoryName(filename)).Name;

Path.GetDirectoryName(filename);

OpenFileDialog choofdlog = new OpenFileDialog();
choofdlog.Filter = "All Files (*.*)|*.*";
choofdlog.FilterIndex = 1;
choofdlog.Multiselect = true;

if (choofdlog.ShowDialog() == DialogResult.OK)    
{     
    string sFileName = choofdlog.FileName; 
    string[] arrAllFiles = choofdlog.FileNames; //used when Multiselect = true           
}

FolderBrowserDialog fbd = new FolderBrowserDialog();
fbd.Description = "Custom Description"; 

if (fbd.ShowDialog() == DialogResult.OK)
{
    string sSelectedPath = fbd.SelectedPath;
}

string fileName = @"test.txt";
    string currentDirectory = Directory.GetCurrentDirectory();
    string[] fullFilePath = Directory.GetFiles(currentDirectory, filename, SearchOption.AllDirectories);