Use Path.Combine instead of Concatenating Paths

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I always advice developers to use System.IO.Path.Combine instead of doing string path concatenation. Here’s why! While concatenating paths in your .NET applications, I often come across the following code:

This code is buggy! You may not realize it at the first glance, but the output produced is

C:\MyFilessomefile.txt

The folderPath does not end with a valid separator character i.e a trailing slash is missing after ‘\’. Now if you write the following code using Path.Combine, the output is as follows:

// code from DevCurry.com
string folderPath = "C:\\MyFiles";
string filePath = "somefile.txt";

string entirePath = folderPath + filePath;
Console.WriteLine("Using String Concat :\n" + entirePath);

entirePath = Path.Combine(folderPath, filePath);
Console.WriteLine("\nUsing Path.Combine :\n" + entirePath);

As you can see, a separator is appended to folderPath before concatenation. So get into the habit of using Path.Combine in your application and it will save you a lot of time during application maintenance.

There are many more similar checks that are taken care of if you are using Path.Combine. It has 4 overloads that you can check here

I would love to see this API enhanced in .NET 5 to allow for Absolute path conversion and path validity check.

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About The Author

Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

Follow him on twitter @suprotimagarwal.