fig04_17.pl

PERL语言资料 可以用于PERL程序设计

#!/usr/bin/perl
# Fig. 4.17: fig04_17.pl
# Demonstrates hash functions keys, values, each and reverse.

%presidents = ( George => "Washington",
                Abe    => "Lincoln",
                Thomas => "Jefferson",
                Harry  => "Truman" );
      
# obtain the list of keys and display each key-value pair
@keys = keys( %presidents );

while ( $key = pop( @keys ) ) {
   print "$key => $presidents{ $key }\n";
}

# display the list of values
@values = values( %presidents );
print "\nThe values of the hash are:\n@values\n\n";

# reverse the hash and use function each to get each pair
print "%presidents with its keys and values reversed\n";
%hash = reverse( %presidents );

while ( ( $key, $value ) = each( %presidents ) ) {
   print "$key => $value\n";
}

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