Functions fc

Daftar Isi

• fc EXPR

• fc

  Returns the casefolded version of EXPR. This is the internal functionimplementing the \F escape in double-quoted strings.

  Casefolding is the process of mapping strings to a form where casedifferences are erased; comparing two strings in their casefoldedform is effectively a way of asking if two strings are equal,regardless of case.

  Roughly, if you ever found yourself writing this

   lc($this) eq lc($that)  # Wrong!
   
   # or
   
   uc($this) eq uc($that)  # Also wrong!
   
   # or
   
   $this =~ /\Q$that/i # Right!
   

  Now you can write

   fc($this) eq fc($that)
   

  And get the correct results.

  Perl only implements the full form of casefolding.For further information on casefolding, refer tothe Unicode Standard, specifically sections 3.13 Default Case Operations,4.2 Case-Normative, and 5.18 Case Mappings,available at http://www.unicode.org/versions/latest/, as well as theCase Charts available at http://www.unicode.org/charts/case/.

  If EXPR is omitted, uses $_.

  This function behaves the same way under various pragma, such as in a locale,as lc does.

  While the Unicode Standard defines two additional forms of casefolding,one for Turkic languages and one that never maps one character into multiplecharacters, these are not provided by the Perl core; However, the CPAN moduleUnicode::Casing may be used to provide an implementation.

  This keyword is available only when the "fc" feature is enabled,or when prefixed with CORE::; See feature. Alternately,include a use v5.16 or later to the current scope.