arrays - 无法解决的 perl 错误？

Question

use strict;
my @array = ();
my @nums = [3, 4];
foreach my $i ( 0 .. 10 ) {
    foreach my $j ( 0 .. 10 ) {
        $nums[0] = 4+1;
        push @{ $array[$i] }, @nums;
    }
}
print $array[6][2][0]. "\n";

如果他们运行代码，就会发现这运行不正常。但是，如果您注释掉“$nums[0] = 4+1;”这一行，它运行良好。到底是怎么回事？只能将不可变数组推送到其他数组吗？

Answer 1

@nums 是一个数组，您分配给一个数组引用(使用方括号 [])。因此，将其更改为适当的数组声明:my @nums = (3, 4);

use strict;
use Data::Dump;

my @array = ();
my @nums = (3, 4);
foreach my $i ( 0 .. 10 ) {
    foreach my $j ( 0 .. 10 ) {
        $nums[0] = 4+1;
        push @{ $array[$i] }, @nums;
    }
}

dd @array;

#-- output:
(
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
  [5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4],
)