Re2: Check for existence in a hash of hashes

$a{foo}{bar} = 'blah';

print "Yep\n" if exists $a{foo} && $a{foo}{bar};
print "Nope\n" if exists $a{bar}{baz};
print "Whoops!\n" if exists $a{bar};
[download]

------
We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Comment on Re2: Check for existence in a hash of hashes Download Code

Replies are listed 'Best First'.
Re: Re2: Check for existence in a hash of hashes by Fletch (Bishop) on Mar 27, 2002 at 18:51 UTC
You've created `$a{bar}` by your second check, just as `perldoc -f exists` explains. Although the deepest nested array or hash will not spring into existence just because its existence was tested, any intervening ones will. Thus "$ref->{"A"}" and "$ref->{"A"}->{"B"}" will spring into existence due to the existence test for the $key element above. This happens anywhere the arrow operator is used, including even:...	[reply] [d/l] [select]
Re4: Check for existence in a hash of hashes by dragonchild (Archbishop) on Mar 27, 2002 at 18:57 UTC
I know that. You know that. Did the original poster know that? Did all the readers of this thread know that? When you post a solution, you should post the common caveats, gimmes, and gotchas as well. Otherwise, those who may not be as fluent as the saints will get frustrated. ------ We are the carpenters and bricklayers of the Information Age. Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.	[reply]