我有一个简单的哈希，并希望以$ value标准返回$ key。也就是说，对于第14行，我需要返回$ $“$”的$键的代码？
1 #!/usr/bin/perl
2
3 # This program creates a hash then
4 # prints out what is in the hash
5
6 %fruit = (
7 'apple' => ['red','green'],8 'kiwi' => 'green',9 'banana' => 'yellow',10 );
11
12 print "The apple is @{$fruit{apple}}.\n";
13 print "The kiwi is $fruit{kiwi}.\n";
14 print "What is yellow? ";
解决方法
grep是这项工作的正确工具：
my @all_matches = grep { $fruit{$_} eq 'yellow' } keys %fruit;
print("$_ ") foreach @matching_keys;
my ($any_match) = grep { $fruit{$_} eq 'yellow' } keys %fruit;