#!/usr/bin/perl --
use strict;
use warnings;
local $\ = $/;
my @f = qw(name John number 7 status unknown);
print do {
    my $i = -2;
    join q/&/, map { $i += 2; join q/=/, $f[$i], $f[ $i + 1 ] } 0 ..( $#f / 2 );
};
print join q/&/, map { $_ % 2 ? () : join q/=/, $f[$_], $f[ $_ + 1 ] } 0 .. $#f;
print join q/&/,
    map {
        $_ % 2
        ? ()
        : join q/=/, $f[$_], $f[ $_ + 1 ]
    } 0 .. $#f;
__END__
name=John&number=7&status=unknown
name=John&number=7&status=unknown
name=John&number=7&status=unknown