Exercise - Work with paths

• 6 minutes

The .NET Path class and Directory.GetCurrentDirectory are two ways to define and compose file-system paths.

In the previous exercise, you wrote a program that iterates through a folder to find any of the sales.json files in it or any subfolders.

In this exercise, you use the Path class and Directory.GetCurrentDirectory to improve the program so it finds any file with a .json extension.

Use the current directory and combine paths

In the current Program.cs code, you're passing the static location of the stores folder. Now, we'll change that code to use the Directory.GetCurrentDirectory value instead of passing a static folder name.

1. In the editor, insert the following code above the first line of Program.cs file. This code uses the Directory.GetCurrentDirectory method to obtain the path for the current directory and store it in a new variable currentDirectory:

   var currentDirectory = Directory.GetCurrentDirectory();
   

2. Insert the following code after the line that you just added. This code uses the Path.Combine method to create the full path to the stores directory and store it in a new variable storesDirectory:

   var storesDirectory = Path.Combine(currentDirectory, "stores");
   

3. Replace the string stores in the FindFiles function call with the new variable storesDirectory:

   var salesFiles = FindFiles(storesDirectory);
   

   The top of your file should now look similar to the following snippet:

   var currentDirectory = Directory.GetCurrentDirectory();
   var storesDirectory = Path.Combine(currentDirectory, "stores");
   var salesFiles = FindFiles(storesDirectory);
   
   foreach (var file in salesFiles)
   {
       Console.WriteLine(file);
   }
   

4. Press Ctrl+S (or Cmd+S macOS) to save the file.

5. Run the program from the command line:

   dotnet run
   

6. The program should show the following output:

   /home/username/dotnet-files/stores/sales.json  
   /home/username/dotnet-files/stores/201/sales.json  
   /home/username/dotnet-files/stores/202/sales.json  
   /home/username/dotnet-files/stores/203/sales.json  
   /home/username/dotnet-files/stores/204/sales.json  
   

   Notice that the file names returned include the full system path. This path is included because Directory.GetCurrentDirectory method returns the full path to the current location.

Find all .json files

Instead of looking for only sales.json files, the program needs to search for any file with a .json extension. To do that, you can use the Path.GetExtension method to check the extension for each file.

1. In the foreach loop that iterates through foundFiles, insert the following line of code above the if statement to define a new variable extension. This code uses the Path.GetExtension method to get the extension of each file.

       var extension = Path.GetExtension(file);
   

2. Change the if statement to look like the following line of code. This statement checks whether the file's extension is equal to .json.

          if (extension == ".json")
   

   The foreach loop should look similar to the following code:

   foreach (var file in foundFiles)
   {
       var extension = Path.GetExtension(file);
       if (extension == ".json")
       {
           salesFiles.Add(file);
       }
   }
   

3. Press Ctrl+S / Cmd+S to save the file.

4. Run the program from the command line:

   dotnet run
   

   The output now shows all .json files in each of the store ID directories:

   /home/username/dotnet-files/stores/sales.json  
   /home/username/dotnet-files/stores/201/sales.json
   /home/username/dotnet-files/stores/201/salestotals.json  
   /home/username/dotnet-files/stores/202/sales.json
   /home/username/dotnet-files/stores/202/salestotals.json    
   /home/username/dotnet-files/stores/203/sales.json  
   /home/username/dotnet-files/stores/203/salestotals.json  
   /home/username/dotnet-files/stores/204/sales.json  
   /home/username/dotnet-files/stores/204/salestotals.json  
   

Great job! You've used the Path class and the Directory.GetCurrentDirectory method to make the program much more robust. In the next unit, you'll learn how to create directories and move files between locations.

Got stuck?

If you got stuck at any point in this exercise, here's the completed code. Remove everything in Program.cs and replace it with this solution:

var currentDirectory = Directory.GetCurrentDirectory();
var storesDirectory = Path.Combine(currentDirectory, "stores");

var salesFiles = FindFiles(storesDirectory);
    
foreach (var file in salesFiles)
{
    Console.WriteLine(file);
}

IEnumerable<string> FindFiles(string folderName)
{
    List<string> salesFiles = new List<string>();

    var foundFiles = Directory.EnumerateFiles(folderName, "*", SearchOption.AllDirectories);

    foreach (var file in foundFiles)
    {
        var extension = Path.GetExtension(file);
        if (extension == ".json")
        {
            salesFiles.Add(file);
        }
    }

    return salesFiles;
}