fig13_14.pl

PERL语言资料 可以用于PERL程序设计

#!/usr/bin/perl
# Figure 13.14: fig13_14.pl
# Demonstrates symbolic references

use warnings;
use strict;
no strict 'refs';

my ( $choice, @variables );
instructions();

do {
   print( "? " );
   chomp( $choice = <STDIN> );

   if ( $choice eq 'v' ) {
      print( "What variable would you like to add to? " );
      chomp( my $name = <STDIN> );

      if ( !( $$name ) ) {
         push( @variables, $name );
         $$name = 0;
      }

      $$name += 20;
   }

   if ( $choice eq 'p' ) {
      print( "What variable would you like to print? " );
      chomp( my $name = <STDIN> );
      print( "$$name\n" );
   }

   if ( $choice eq 'a' ) {

      foreach my $name ( @variables ) {
         print( "\$$name = $$name\n" );
      }
   }

   instructions() if ( $choice eq 'i' );

} while ( $choice ne 'q' );

sub instructions
{
print <<DONE;
Enter 'v' to add to a variable
Enter 'p' to print a variable
Enter 'a' to print all the variables
Enter 'i' to print the instructions
Enter 'q' to quit
DONE
}

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