Perl by Example - 02

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最新推荐文章于 2022-08-11 22:08:41 发布 · 219 阅读

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本文介绍了一个脚本语言中Hash关联数组的keys函数使用方法。通过示例展示了如何获取Hash关联数组的所有键名，并通过随机顺序及排序后的顺序进行打印。

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.