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C# Snippet Tutorial - Get File Listings [Beginner]


Ok, so can you even begin to tell me how many files you have on your computer? I can't either. There are so many reasons you could need to get file listings in C#, and thanks to the System.IO namespace, doing so is just about as easy as including the namespace itself. Really all you need to do is create a variable, then a loop.

So all the magic happens due to a couple of nice and simple classes in the System.IO namespace, called DirectoryInfo and FileInfo. Really, with these two classes you can do a lot of cool stuff, directory and file wise that is. Not only do these classes make file and directory listing really simple, but they are actually more powerful than they seem.

Anyway, in order to get started, you must first include the System.IO namespace, mainly because it is not used by default. So add it to the top of your code. Next we are going to make a new DirectoryInfo instance, and in this case we are using the root drive of C:\, so your code should look like:
DirectoryInfo fileListing = new DirectoryInfo("C:\\");
 
This code does exactly what you would think, it takes the directory and allows you to get all kinds of information about it. You can use this one variable to find out all kinds of things, anything from directory permissions to the last modified date. Now, this little snippet will only cover the basics, but when you are looking at more, just remember listing files is only the simplest of things you can do.

Now that we have our DirectoryInfo object, we can loop through all the files in that directory and do whatever we like with them. In this case, we are just going to fill a listbox with the full file path. To do this, all we need to do is call the GetFiles() method, which returns an array of FileInfo objects. Each FileInfo has a ton of information on each file, but all we really need is the name right now. So our final code might look something like:
DirectoryInfo fileListing = new DirectoryInfo("C:\\");

foreach (FileInfo file in fileListing.GetFiles())
{
  listBox1.Items.Add(fileListing.ToString() + file.Name);
}
 
Super simple, but lets be honest with ourselves, how often do you want all the files in a directory? Not very often I would think. Luckily, the GetFiles() method has an argument to limit what files you get. This argument is just a string that you can add a search pattern to. So say we want to search for .txt files. Our updated code would look like so:
DirectoryInfo fileListing = new DirectoryInfo("C:\\");

foreach (FileInfo file in fileListing.GetFiles("*.txt"))
{
  listBox1.Items.Add(fileListing.ToString() + file.Name);
}
 
The one downside to using the search pattern is that you can only use one of them. As far as I know you can only use one search pattern in the string, so in order to get multiple file types, you have to call the method again with a different pattern. That being said, it is not too much of an inconvenience being as easy as it is.

So that is pretty much how you can get the files in a current directory. Super simple and super fast. You can do all kinds of things with the DirectoryInfo and FileInfo classes, so I would check them out if you can.
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