Finding values from array in hash key and return counts of zero

debugcn 投稿 Dev

tavalendo

I have one array which I am checking for values in a hash (which I created). The idea is to check each element of the array if exists in the hash keys. If it does not exists, it should say that the non-existent element appears zero times. The hash I created to count frequency of numbers on a second array.

Here's what I did:

use strict;
use warnings;

sub main {
    
    my @Source = ("A", "B", "D");
    my @ArrToHash = ("A", "C", "A", "B", "E", "F");
    
    my %hashy;
    ++$hashy{$_} for @ArrToHash;
    
    foreach my $e (@Source) {
        if (exists $hashy{$e}) {
            print "$e are $hashy{$e}\n";
        }
    }
}
main();

I am getting

A are 2

B are 1

While in reality I would like:

A are 2

B are 1

D are 0

Any clue? How to fix my code?

AnFi

    if (exists $hashy{$e}) {
        print "$e are $hashy{$e}\n";
    }else{
        print "$e are 0\n";
    }

    printf "%s are %d\n", $e, $hashy{$e} // 0 ;

Comment:
I prefer $hashy{$e} // 0. It returns $hashy{$e} if $hashy{$e} exits and it is not undef.
Ikegami prefers $hashy{$e} || 0. It returns 0 also when $hashy{$e} is an empty string. It works with older perl versions without // operator support.
IMHO It is a matter of "style-guide" in most situations.

この記事はインターネットから収集されたものであり、転載の際にはソースを示してください。

侵害の場合は、連絡してください[email protected]

編集2021-06-6

コメントを追加

サインイン

分類Dev

How to return a value from a function , use that value to make a math formula and push the solution(key/value) to an array of objects?

分類Dev

Related 関連記事

記事