Cursus Raku / Addendum 🆕 / Omnia coniungere / Incepta parva mixta / Exercises / Calculator notationis Polonicae inversae

Solutio: Calculator notationis Polonicae inversae

Ecce solutio possibilis huius exercitationis.

Codex

my $expression = '3 4 + 5 *';
my @stack;

for $expression.words -> $token {
    if $token ~~ / ^ \d+ $ / {
        @stack.push($token.Int);
    }
    else {
        my $b = @stack.pop;
        my $a = @stack.pop;
        @stack.push( do given $token {
            when '+' { $a + $b }
            when '-' { $a - $b }
            when '*' { $a * $b }
            when '/' { $a / $b }
        });
    }
}

say @stack[0];

🦋 Inveni codicem fontem in archivo rpn-calculator.raku.

Exitus

35

Commentarii

  1. Numeri in acervum immittuntur. Operator duos valores recentissimos eximit, eos componit, et effectum reponit — essentia aestimationis postpositivae.

  2. do given $token operatorem in arithmeticam rectam vertit, et ordo $a deinde $b (ordine inverso exemptorum) subtractionem et divisionem recte servat.

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