Perl by Example
5.5. Hash (Associative Array)
Functions
5.5.1. The keys Function
The keys
function returns, in random order, an array whose elements are the keys of a
hash (see "The values Function" and "The each
Function").
Format
keys(ASSOC_ARRAY)
keys ASSOC_ARRAY
Example 5.53.
(In Script)
# The keys function returns the keys of a hash
1 %weekday= (
'1'=>'Monday',
'2'=>'Tuesday',
'3'=>'Wednesday',
'4'=>'Thursday',
'5'=>'Friday',
'6'=>'Saturday',
'7'=>'Sunday',
);
2 foreach $key ( keys(%weekday) ){print "$key ";}
print "\n";
3 foreach $key ( sort keys(%weekday) ){print $key ;}
print "\n";
(Output)
2 7 1 2 3 4 5 6
3 1 2 3 4 5 6 7
Explanation
[*]
The hash %weekday is assigned
keys and values.
[*]
For each value in %weekday, call
the keys function to get
the key. Assign the key value to the scalar $key and print it in random
order.
[*]
Now the keys are sorted and
printed.
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