perl的引用数组的解引用二维数组的引用hash哈希又叫散列的引用

perl的引用，类似C语言的指针；意义都是指向一个内存空间的地址。比如下述例子中，脚本输出的信息SCALAR(0x7836d0)代表标量数据的存储地址；ARRAY(0x93d6d0)代表数组数据的存储地址。

引用一般会包含“定义引用”，“解引用”两个步骤。“定义引用”是为数据定义内存地址；“解引用”是取内存地址里的数据。

引用的变量是标量类型，那么解引用就必须用标量符号$； 引用的变量是数组类型，那么解引用就必须用数组符号@； 引用的变量是散列类型，那么解引用就必须用散列符号%； …. 总之，解引用和定义引用的数据类型，要保持一致。

另外，解引用的过程中，要关心地址的个数，从而决定是用标量还是数组收集。

perl的引用

qilei@AFAAW-704030720:~/array_2d$ cat 1.pl #!/usr/bin/perl use strict; use warnings; my $value = 10; my $pointer = \$value; print "Pointer Address $pointer of $value \n"; print "What Pointer *($pointer) points to $$pointer\n"; qilei@AFAAW-704030720:~/array_2d$ ./1.pl Pointer Address SCALAR(0x7836d0) of 10 What Pointer *(SCALAR(0x7836d0)) points to 10 qilei@AFAAW-704030720:~/array_2d$

数组的解引用

引用的变量是数组类型，那么解引用就必须用数组符号@。 非数组类型的引用变量同理，即解引用和定义引用的数据类型都要注意保持一致。

qilei@AFAAW-704030720:~/array_2d$ cat 2.pl #!/usr/bin/perl use strict; use warnings; my @names =(1,2,3); print "$#names\n@names\n"; my $address = \@names; sub listem{ my ($list) = @_; print $list."\n"; print (@$list[1],"\n"); } &listem(\@names); qilei@AFAAW-704030720:~/array_2d$ ./2.pl 2 1 2 3 ARRAY(0x93d6d0) 2 qilei@AFAAW-704030720:~/array_2d$

二维数组的引用

qilei@AFAAW-704030720:~/array_2d$ cat run.pl #!/usr/bin/perl use strict; use warnings; my @array1=("a1","b1","c1","d1"); my @array2=("a2","b2","c2","d2"); my @array3=("a3","b3","c3","d3"); my @array_2d=(@array1,@array2,@array3); print "@array_2d"; print "\n"; print "$array_2d[1]"; print "\n"; ################ @array_2d=(\@array1,\@array2,\@array3); print "@array_2d"; print "\n"; print "$array_2d[1]"; print "\n"; print "$array_2d[1][1]"; print "\n"; qilei@AFAAW-704030720:~/array_2d$ ./run.pl a1 b1 c1 d1 a2 b2 c2 d2 a3 b3 c3 d3 b1 ARRAY(0x175a6e0) ARRAY(0x175a788) ARRAY(0x175a878) ARRAY(0x175a788) b2 qilei@AFAAW-704030720:~/array_2d$

hash（哈希，又叫散列）的引用

hash数据类型，不能直接用print "%var"去打印。究其原因，个人暂时理解为，hash数据存储方式与标量数组不一样，是key和value组合在一起的；所以不能直接打印。此时用Data::Dumper package打印hash数据，方便阅读。

但是，通过实践发现，print %var;也可以打印hash数据，但是格式不好看，不容易阅读。

qilei@AFAAW-704030720:~/array_2d$ cat 3.pl #!/usr/bin/perl use strict; use warnings; use Data::Dumper; my %parameters=("p1"=>"xx1", "p2"=>"xx2", "p3"=>"xx3"); print %parameters; print "\n"; print Dumper(\%parameters); print "\n"; print "$parameters{p2}"; print "\n"; my $address = \%parameters; print Dumper($address); print "\n"; print %$address; print "\n"; print $$address{p3}; print "\n"; qilei@AFAAW-704030720:~/array_2d$ ./3.pl p3xx3p1xx1p2xx2 $VAR1 = { 'p3' => 'xx3', 'p1' => 'xx1', 'p2' => 'xx2' }; xx2 $VAR1 = { 'p3' => 'xx3', 'p1' => 'xx1', 'p2' => 'xx2' }; p3xx3p1xx1p2xx2 xx3 qilei@AFAAW-704030720:~/array_2d$