如何在Perl中创建哈希散列？ [英] How do I create a hash of hashes in Perl?

问题描述

基于我目前对Perl中哈希的理解，我希望这段代码能够打印出hello world。它反而不打印任何东西。

 ％a =（）; 
 
％b =（）; 
 $ b {str} =hello; 
 $ a {1} =％b; 
 
 $ b =（）; 
 $ b {str} =world; 
 $ a {2} =％b; 
 
打印$ a {1} {str} $ a {2} {str}; 
  

我假设哈希就像数组一样，为什么我不能使哈希包含另一个？

解决方案

1. 您应该始终使用use strict在您的程序中。
   

2. 使用引用和匿名哈希。

 使用strict;使用警告; 
 my％a; 
 
 my％b; 
 $ b {str} =hello; 
 $ a {1} = {％b}; 
 
％b =（）; 
 $ b {str} =world; 
 $ a {2} = {％b}; 
 
打印$ a {1} {str} $ a {2} {str}; 
  

{％b} 创建对散列％b 的副本的引用。您需要在这里复制，因为您稍后将其清空。

Based on my current understanding of hashes in Perl, I would expect this code to print "hello world." It instead prints nothing.

%a=();

%b=();
$b{str} = "hello";  
$a{1}=%b;

$b=();
$b{str} = "world";
$a{2}=%b;

print "$a{1}{str}  $a{2}{str}"; 

I assume that a hash is just like an array, so why can't I make a hash contain another?

解决方案

1. You should always use "use strict;" in your program.

2. Use references and anonymous hashes.

use strict;use warnings;
my %a;

my %b;
$b{str} = "hello";  
$a{1}={%b};

%b=();
$b{str} = "world";
$a{2}={%b};

print "$a{1}{str}  $a{2}{str}";

{%b} creates reference to copy of hash %b. You need copy here because you empty it later.

这篇关于如何在Perl中创建哈希散列？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！