CODEWITHSUNDEEP
c#
Jim Lahman
Jim Lahman

Reputation: 2757

Null in directory name does not return exception when it is created

I just encountered a situation where a colleague is creating directories from a list. It just so happens that one of the items in the list is null but an exception is not null.

To satisfy my curiosity, I wrote a test program to mimic what he was doing. This test programo attempts to create a null directory in c:\Temp, which already exists. I would've expected a Null Exception to be thrown but no exception was thrown.

Here's my test program.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace CreateNullDirectory
{
  class Program
  {
    static void Main(string[] args)
    {
        String DirectoryName = null;

        String FullDirectoryName = string.Format("c:\\Temp\\{0}",DirectoryName);

        Console.WriteLine(string.Format("Creating Directory {0}", FullDirectoryName));

        try
        {
            Directory.CreateDirectory(FullDirectoryName);
            Console.WriteLine(string.Format("Successfully created directory {0}", FullDirectoryName));
        }
        catch (Exception ex)
        {
            Console.WriteLine(string.Format("Error creating {0} - {1}", FullDirectoryName, ex.Message));
        }

        Console.ReadLine();

    }
  }
}

Here is the output:

enter image description here

Is CreateDirectory ignoring the terminating null and I'm only attempting to create C:\Temp which already exists?

Upvotes: 0

Views: 1695

Answers (1)

Dave Zych
Dave Zych

Reputation: 21887

All you're doing is calling Directory.CreateDirectory("C:\Temp"), because passing a null value in format string returns string.Empty.

CreateDirectory either creates the directory if it doesn't exist, or does nothing if it already exists.

Upvotes: 2

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