Perl 6 - Starting with the basics - Strings(looping and counting, index function, substr function)

Think Perl 6

開発環境

• macOS Sierra - Apple (OS)
• Emacs (Text Editor)
• Perl 6 (プログラミング言語)
• Rakudo(コンパイラ、実装)

Think Perl 6: How to Think Like a Computer Scientist (Laurent Rosenfeld(著)、Allen B. Downey(著)、Oreilly & Associates Inc)のPart 1(Starting with the basics)、Chapter 7(Strings)の Exercises 7-1.を取り組んでみる。

Exercises 7-1.

コード(Emacs)

#!/usr/bin/env perl6
# -*- coding: utf-8 -*-

sub counter1(Str $word, Str $letter) {
    my $count = 0;
    my $i = 0;
    while (True) {
        my $j = $word.index($letter, $i);
        if ($j) {
            $count++;
            $i = $j + 1;
        } else {
            last;
        }
    }    
    $count;
}

say counter1('banana', 'a');

sub counter2(Str $word, Str $letter) {
    my $count = 0;
    for 0..$word.chars -> $i {
        $count++ if $word.substr($i, 1) eq $letter;
    }
    $count;
}

say counter2('banana', 'a');

入出力結果(Terminal, REPL)

$ ./sample1.pl
3
3
$