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

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Contributed by ambrus on Sep 05, 2011 at 10:27 UTC
Q&A  > Data Structures

Answer: How to check whether a hash is empty (has no keys)?
contributed by ambrus

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 }

If you want to be very explicit, you can also write

if (!!%foo) { ... }
if (scalar %foo) { ... }
if (0+%foo) { ... }
Answer: How to check whether a hash is empty (has no keys)?
contributed by davido

keys, in scalar context returns the number of keys in the hash.

if( keys %hash ) { # There are keys } else { # There are no keys }

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