Recipe 11.15 Parsing a Path

Problem

You need to separate the constituent parts of a path and place them into separate variables.

Solution

Use the static methods of the Path class:

public static void ParsePath(string path)
{
    string root = Path.GetPathRoot(path);
    string dirName = Path.GetDirectoryName(path);
    string fullFileName = Path.GetFileName(path);
    string fileExt = Path.GetExtension(path);
    string fileNameWithoutExt = Path.GetFileNameWithoutExtension(path);
    StringBuilder format = new StringBuilder( );
    format.Append("ParsePath of {0} breaks up into the following" +
           "pieces:\r\n\tRoot: {1}\r\n\t");
    format.Append("Directory Name: {2}\r\n\tFull File Name: {3}\r\n\t");
    format.Append("File Extension: {4}\r\n\tFile Name Without Extension: {5}\r\n");
    Console.WriteLine(format.ToString( ),path,root,dirName,
           fullFileName,fileExt,fileNameWithoutExt);
}

If the string @"c:\test\tempfile.txt" is passed to this method, the output would look like this:

ParsePath of C:\test\tempfile.txt breaks up into the following pieces:
        Root: C:\
        Directory Name: C:\test
        Full File Name: tempfile.txt
        File Extension: .txt
        File Name Without Extension: tempfile

Discussion

The Path class contains methods that can be used to parse a given path. Using these classes is much easier and less error-prone than writing path- and filename-parsing code. There are five main methods used to parse a path: GetPathRoot, GetDirectoryName, GetFileName, GetExtension, and GetFileNameWithoutExtension. Each has a single parameter, path, which represents the path to be parsed:

GetPathRoot

This method returns the root directory of the path. If no root is provided in the path, such as when a relative path is used, this method returns an empty string, not null.

GetDirectoryName

This method returns the complete path to a file.

GetFileName

This method returns the filename, including the file extension. If no filename is provided in the path, this method returns an empty string, not null.

GetExtension

This method returns the file's extension. If no extension is provided for the file or no file exists in the path, this method returns an empty string, not null.

GetFileNameWithoutExtension

This method returns the root filename without the file extension. If no extension is provided on the file, this method returns an empty string, not null.

Be aware that these methods do not actually determine whether the drives, directories, or even files exist on the system that runs these methods. These methods are string parsers and if you pass one of them a string in some strange format (such as "\\ZY:\foo"), it will try to do what it can with it anyway:

ParsePath of \\ZY:\foo breaks up into the following pieces:
        Root: \\ZY:\foo
        Directory Name:
        Full File Name: foo
        File Extension:
        File Name Without Extension: foo

These methods will, however, throw an exception if illegal characters are found in the path. To determine whether files or directories exist, use the static Directory.Exists or File.Exists methods.

See Also

See the "Path Class" topic in the MSDN documentation.