条件操作符?:|建立二维数组的简洁形式

 1 ```perl
 2 #!/usr/bin/perl
 3 
 4 use strict;
 5 use warnings;
 6 
 7 my @arr;
 8 
 9 foreach(1..4)
10 {
11     push @arr,[0,0,0,0];
12 }
13 my ($i,$j);
14 
15 for($i=0;$i<5;$i++)
16 {
17     for($j=0;$j<5;$j++)
18     {
19         print "$arr[$i][$j]\n";
20     }
21 }
22 
23 #push @arr,[(0) x 4]foreach 1..4
24 
25 my $change=3;my $b=4;
26 
27 $change=$b==0 ? 'first':'end';print "\$change=$change,\$b=$b\n";
28 
29 #$change=end,$b=4
30 
31 my $n = '';$n = $n-2;print "$n\n";
32 
33 #-2
34 
35 my $m = 0;$n = $m == 0? 'null == 0':'null != 0';print "$n\n";
36 
37 ```