How to check whether a hash is empty (has no keys)?

ambrus has asked for the wisdom of the Perl Monks concerning the following question: ⭐ (data structures)

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Re: How to check whether a hash is empty (has no keys)?⭐ by ambrus (Abbot) on Sep 05, 2011 at 10:32 UTC
Just use the name of the hash in scalar context, such as `if (%foo) { # %foo has at least one key } else { # %foo has no keys }` [download] If you want to be very explicit, you can also write `if (!!%foo) { ... }` [download] or `if (scalar %foo) { ... }` [download] or `if (0+%foo) { ... }` [download]	[reply] [d/l] [select]
Re: How to check whether a hash is empty (has no keys)?⭐ by davido (Cardinal) on Sep 06, 2011 at 02:13 UTC
keys, in scalar context returns the number of keys in the hash. `if( keys %hash ) { # There are keys } else { # There are no keys }` [download]	[reply] [d/l]