在Perl中取消引用
在Perl中解引用会将值从参考点返回到位置。要取消引用的引用，只需使用$，@或％作为引用变量的前缀，具体取决于引用是指向标量，数组还是哈希。以下是解释概念的示例-
示例
#!/usr/bin/perl
$var = 10;
# Now $r has reference to $var scalar.
$r = \$var;
# Print value available at the location stored in $r.
print "Value of $var is : ", $$r, "\n";
@var = (1, 2, 3);
# Now $r has reference to @var array.
$r = \@var;
# Print values available at the location stored in $r.
print "Value of @var is : ", @$r, "\n";
%var = ('key1' => 10, 'key2' => 20);
# Now $r has reference to %var hash.
$r = \%var;
# Print values available at the location stored in $r.
print "Value of %var is : ", %$r, "\n";输出结果
执行以上程序后，将产生以下结果-
Value of 10 is : 10 Value of 1 2 3 is : 123 Value of %var is : key220key110
如果不确定变量类型，则可以很容易地使用ref来了解其类型，如果ref的参数是引用，它将返回以下字符串之一。否则，它返回false-
SCALAR ARRAY HASH CODE GLOB REF
示例
让我们尝试以下示例-
#!/usr/bin/perl
$var = 10;
$r = \$var;
print "Reference type in r : ", ref($r), "\n";
@var = (1, 2, 3);
$r = \@var;
print "Reference type in r : ", ref($r), "\n";
%var = ('key1' => 10, 'key2' => 20);
$r = \%var;
print "Reference type in r : ", ref($r), "\n";输出结果
执行以上程序后，将产生以下结果-
Reference type in r : SCALAR Reference type in r : ARRAY Reference type in r : HASH
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