Reference Basic in Perl

小洪維尼

Making References  
　　References can be created in several ways.
　　By using the backslash operator on a variable, subroutine, or value. (This works much like the & (address-of) operator in C.)   This typically creates another reference to a variable, because there's already a reference to the variable in the symbol table.  But the symbol table reference might go away, and you'll still have the reference that the backslash returned.  Here are some examples:

•     $scalarref = \$foo;
  
•     $arrayref  = \@ARGV;
  
•     $hashref   = \%ENV;
  
•     $coderef   = \&handler;
  
•     $globref   = \*foo;
  

Using References
  
　　That's it for creating references.  By now you're probably dying to
know how to use references to get back to your long-lost data.  There
are several basic methods.

• Anywhere you'd put an identifier (or chain of identifiers) as part of a
  　　variable or subroutine name, you can replace the identifier with a
  BLOCK returning a reference of the correct type.  In other words, the
  previous examples could be written like this:
  
  
  
  
  •     $bar = ${$scalarref};
    
  •     push(@{$arrayref}, $filename);
    
  •     ${$arrayref}[0] = "January";
    
  •     ${$hashref}{"KEY"} = "VALUE";
    
  •     &{$coderef}(1,2,3);
    
  •     $globref->print("output\n");  # iff IO::Handle is loaded