gives the file extension for a file name.

Details and Options

  • FileExtension["name.ext"] gives "ext".
  • FileExtension gives the extension that appears after the last . in a file name.
  • If there are multiple endings to a file name, separated by ., FileExtension gives only the last one.
  • FileExtension gives "" if there is no file extension, if the file name has the form of a directory name, or ends with a . character.
  • FileExtension ignores any directory specification.
  • FileExtension by default assumes pathname separators and other conventions suitable for your operating system.
  • FileExtension[,OperatingSystem->"os"] uses the conventions of the specified operating system. Possible choices are "Windows", "MacOSX", and "Unix".
  • FileExtension just operates on names of files; it does not actually search for the file specified.
  • FileExtension[File["file"]] is also supported.


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Basic Examples  (1)

Find the file extension of a string:

Scope  (1)

Find the extension of the file specified by the File object:

Possible Issues  (1)

The period is not part of the file extension:

Or the file base name:

Introduced in 2008
Updated in 2016