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Programming Perl

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3.2.30 each

each HASH

This function returns a two-element list consisting of the key and value for the next value of a hash. With successive calls to each you can iterate over the entire hash. Entries are returned in an apparently random order. When the hash is entirely read, a null list is returned (which, when used in a list assignment, produces a false value). The next call to each after that will start a new iteration. The iterator can be reset either by reading all the elements from the hash, or by calling the keys function in scalar context. You must not add elements to the hash while iterating over it, although you are permitted to use delete. In a scalar context, each returns just the key, but watch out for false keys.

There is a single iterator for each hash, shared by all each, keys, and values function calls in the program. This means that after a keys or values call, the next each call will start again from the beginning. The following example prints out your environment like the printenv(1) program, only in a different order:

while (($key,$value) = each %ENV) {
    print "$key=$value\n";
}

See also keys and values.


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