獲取

Question

我試圖讓哈希散列的鍵哈希散列的鍵，總是有錯誤：

use strict; 

my %oop_hash =(); 
$oop_hash{'wfh'}{'ppb'} = "451103"; 
print (keys $oop_hash{'wfh'})."\n"; #1st try 
print (keys %oop_hash{'wfh'})."\n"; #2nd try 

我怎樣才能哈希散列的鑰匙？

Answer 1

這是一個有點棘手。正確的語法是

keys %{$oop_hash{'wfh'}} 

此外，正如你所寫的，你的print statement will not quite do what you want。由於Perl解析該行的方式，"\n"不會附加到該字符串。你必須說：

print +(keys %{$oop_hash{'wfh'}}),"\n"; 
print ((keys %{$oop_hash{'wfh'}}),"\n"); 

Answer 2

那就是：

#!/usr/bin/perl 
use strict; 
use warnings; 

my %oop_hash =(); 
$oop_hash{'wfh'}{'ppb'} = "451103"; 
print join ", ", keys $oop_hash{'wfh'} , "\n"; # "ppb, "