Perl入学式2013年度第5回補講in東京よりmap, grep練習問題の校長の回答

map_grep.pl

#!/usr/bin/env perl
use strict;
use warnings;
use DDP;

my @files = qw/papix.pl moznion.pm macopy.py boolfool.vim/;

sub map_bak {
    my $array_ref = shift;
    return [ map {$_ . '.bak'} @{$array_ref} ];
}

my $map_bak = map_bak(\@files);
p $map_bak;

sub grep_pl_and_pm {
    my $array_ref = shift;
    return [ grep { /\.p[lm]$/} @{$array_ref} ] ;
}

my $grep_pl_and_pm = grep_pl_and_pm (\@files);
p $grep_pl_and_pm;

実行結果は以下。

\ [
    [0] "papix.pl.bak",
    [1] "moznion.pm.bak",
    [2] "macopy.py.bak",
    [3] "boolfool.vim.bak"
]
\ [
    [0] "papix.pl",
    [1] "moznion.pm"
]