9.9. Syntax Extension

9.9.1. Rationale

  • In other programming languages

9.9.2. Example

  • [:allnum:] == [a-zA-Z0-9]

  • [:alpha:] == [a-zA-Z]

  • [a-Z] == [a-zA-Z]

  • [a-9] == [a-zA-Z0-9]

  • $1 == \1