Extract file extension from file path

Question

How can I extract the extension of a file given a file path as a character? I know I can do this via regular expression regexpr(\"\\\\.([[:alnum:]]+)$\", x), b

Answer 1

Let me extend a little bit great answer from https://stackoverflow.com/users/680068/zx8754

Here is the simple code snippet

  # 1. Load library 'tools'
  library("tools")

  # 2. Get extension for file 'test.txt'
  file_ext("test.txt")

The result should be 'txt'.