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Perl 5 version 12.2 documentation
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# ref

Perl functions A-Z | Perl functions by category | The 'perlfunc' manpage

- ref EXPR

- ref

  Returns a non-empty string if EXPR is a reference, the empty string otherwise. If EXPR is not specified, `$_` will be used. The value returned depends on the type of thing the reference is a reference to. Builtin types include:

          SCALAR    ARRAY    HASH    CODE    REF    GLOB    LVALUE    FORMAT    IO    VSTRING    Regexp

  If the referenced object has been blessed into a package, then that package name is returned instead. You can think of `ref` as a `typeof` operator.

          if (ref($r) eq "HASH") {        print "r is a reference to a hash.\n";    }    unless (ref($r)) {        print "r is not a reference at all.\n";    }

  The return value `LVALUE` indicates a reference to an lvalue that is not a variable. You get this from taking the reference of function calls like `pos()` or `substr()`. `VSTRING` is returned if the reference points to a version string.

  The result `Regexp` indicates that the argument is a regular expression resulting from `qr//`.

  See also perlref.