错误 - “全局符号需要明确的包名" [英] Error - 'global symbol requires explicit package name'

问题描述

我正在尝试为矩阵乘法编写脚本.它只是一个基本程序，但我无法弄清楚以下错误:

I am trying to write a script for matrix multiplication. Its just a basic program but I am not able to figure it out about the following error :

全局符号@ref_mat1"需要在 multiplication.pl 第 49 行显式包名称.

Global symbol "@ref_mat1" requires explicit package name at multiplication.pl line 49.

全局符号@ref_mat2"需要在 multiplication.pl 第 49 行显式包名称.

Global symbol "@ref_mat2" requires explicit package name at multiplication.pl line 49.

下面是我的脚本:

 #!/usr/bin/perl -w
    use strict;

     my @mat1=(
        [2,3,4],
        [1,2,3],
        [3,4,5]
            );

    my @mat2=(
            [2],
            [3],
            [4]
           );


    my ($i, $j, $k);
    my $r_product=[];

   $r_product= mat_multiplication(\@mat1,\@mat2);

    sub mat_multiplication
        {

         my ($ref_mat1,$ref_mat2)=@_;
         my($mat1_row,$mat1_col)=total_rows_column($ref_mat1);
         my($mat2_row,$mat2_col)=total_rows_column($ref_mat2);
             for($i=0;$i<$mat1_row;$i++)
            {
               for($j=0;$j<$mat2_col;$j++)
                {
                   my $sum=0;
                   for($k=0;$k<$mat1_col;$k++)
                    {
                      $sum=$sum+$ref_mat1[$i][$k]*$ref_mat2[$k][$j];
                    }
                    $r_product->[$1][$j]=$sum;
                }
            } 
            return $r_product;

        }


    sub total_rows_column
             { 
              my($r_mat) =@_;
              my $num_row=@{$r_mat};
              my $num_col=@{$r_mat->[0]};
              return($num_row,$num_col);
             }

我搜索了这个问题并找到了一个链接

I searched for this problem and found one link

'全局符号需要明确的包名'的解释

但是还是无法解决.请看看让我知道我在哪里做错了.

But still not able to resolve it. Please just have a look an let me know where am i doing mistake.

谢谢

推荐答案

$ref_mat1 和 $ref_mat2 是对数组的引用.在 Perl 中，如果您想访问对数组的引用，则不能直接使用 $reference[$idx] —— 必须在引用后使用 -> 运算符像这样:$ref_mat1->[0].

$ref_mat1 and $ref_mat2 are references to arrays. In Perl if you want to access a reference to an array you cannot use $reference[$idx] directly -- you have to use the -> operator after the reference like this: $ref_mat1->[0].

没有它 Perl 认为 $ref_mat1[0] 指的是一个不存在的数组 @ref_mat1.是的，$var 和 @var 可以同时存在，但内容不同，请参见此示例:

Without it Perl thinks that $ref_mat1[0] refers to an array @ref_mat1 which doesn't exist. Yes, both $var and @var can exist at the same time with differing content, see this example:

use strict;
use Data::Dumper;

my $abc = 42;
my @abc = (1, 2, 3);

print Dumper($abc), Dumper(\@abc);

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