条件操作符?:|建立二维数组的简洁形式

```perl
#!/usr/bin/perl

use strict;
use warnings;

my @arr;

foreach(1..4)
{
    push @arr,[0,0,0,0];
}
my ($i,$j);

for($i=0;$i<5;$i++)
{
    for($j=0;$j<5;$j++)
    {
        print "$arr[$i][$j]\n";
    }
}

#push @arr,[(0) x 4]foreach 1..4

my $change=3;my $b=4;

$change=$b==0 ? 'first':'end';print "\$change=$change,\$b=$b\n";

#$change=end,$b=4

my $n = '';$n = $n-2;print "$n\n";

#-2

my $m = 0;$n = $m == 0? 'null == 0':'null != 0';print "$n\n";

```

 建立二维数组方式二：

#!/usr/bin/perl

use strict;
use warnings;

my @arr=qw/ A B C D /;
my @multiarr ;push @multiarr,[@arr];
print "$multiarr[0][0]\n"; 


#A