Circvitvs rectos designare

Formae

Qvid variabilis significet

Plvrimi circvitvs non invenivntvr: componvntvr ex pavcis membris qvae in omnibvs programmatibvs redevnt. Qvodqve membrvm est variabilis cvm initialisatione ante circvitvm, renovatione intra evm et, praesertim, significatione qvae post qvemqve gyrvm valet. Membra per significationem, non per formam, cognoscere id est qvod sinit ea sine errore conivngere.

• Nvmerator valet qvot data tractata sint (vel qvot condicioni satisfaciant). Initialisatvr ad 0, qvia ante primvm gyrvm nvllvm tractatvm est, et renovatvr per ++count, tantvm cvm aliqvid nvmerandvm est.
• Accvmvlator valet conivnctionem datorvm tractatorvm: svmmam eorvm, prodvctvm. Initialisatvr ad elementvm nevtrvm operationis (0 pro svmma, 1 pro prodvcto), qvia svmma nvllorvm datorvm est 0 et prodvctvm nvllorvm datorvm est 1.
• Maximvm valet maximvm datorvm tractatorvm, et minimvm, minimvm. Maximvm nvllorvm datorvm non exstat: ideo initialisatvr primo dato, non nvmero temere electo.
• Excvbitor est valor introitvs qvi non est datvm, sed signvm data finita esse. Forma postvlat vt semel ante circvitvm legatvr et itervm in fine corporis, vt fecit lectio Circvitvs vsqve ad nihilvm svmmans, ita vt condicio qvemqve valorem examinet anteqvam tractetvr, et excvbitor nvmqvam pro dato nvmeretvr.
• Vexillvm est bool qvod indicat vtrvm aliqvid vmqvam inter data tractata acciderit. Initialisatvr ad false et in true transit primo cvm accidit; nvllvs gyrvs posterior id ad false redvcit.

Exemplvm cvm omnibvs membris

Diarivm plvviae millimetra singvlis diebvs delapsa notat. Programma primvm limen legit, deinde mensvras plvrivm diervm, nvmero negativo terminatas, qvi mensvra possibilis non est et excvbitoris loco est; scribit qvot mensvrae sint, mediam earvm, maximvm, qvot dies limen svperaverint et vtrvm aliqvis dies sine plvvia fverit.

#include <iostream>#include <print>​int main(){    double threshold{};    std::cin >> threshold;    int count{0};          // nvmerator: mensvrae tractatae    int aboveCount{0};     // nvmerator: mensvrae svpra limen    double total{0.0};     // accvmvlator: svmma mensvrarvm    double largest{0.0};   // maximvm: valet tantvm si count > 0    bool dryDay{false};    // vexillvm: dies sine pluvia fvit    double value{};    std::cin >> value;    while (std::cin && value >= 0.0) {        if (count == 0 || value > largest) {            largest = value;        }        ++count;        total += value;        if (value > threshold) {            ++aboveCount;        }        if (value == 0.0) {            dryDay = true;        }        std::cin >> value;    }    if (count == 0) {        std::println("Nvllae mensvrae.");    } else {        std::println("Mensvrae: {}; media: {:.2f} mm", count, total / count);        std::println("Maximvm: {:.1f} mm; dies svpra {:.1f} mm: {}", largest, threshold, aboveCount);        std::println("Dies sine pluvia: {}", dryDay ? "ita" : "non");    }}

104.5 0 12.5 21.5 7.5 -1

Mensvrae: 5; media: 9.20 mmMaximvm: 21.5 mm; dies svpra 10.0 mm: 2Dies sine pluvia: ita

Qvattvor decisiones commentarivm merentvr. Condicio count == 0 || value > largest maximvm primo dato initialisat sine lectvra separata: in primo gyro nvmerator 0 valet et assignatio semper fit; in seqventibvs, tantvm si datvm maximvm svperat. Comparatio value == 0.0 exacta est, qvia valor lectvs est, non compvtatvs: cifra 0 in nihilvm exactvm convertitvr, et cavtio lectionis Nvmeri virgvlae flvitantis contra == ad eventvs operationvm pertinet. Condicio circvitvs std::cin continet, vt introitvs qvi sine excvbitore deficit etiam circvitvm finiat. Et media tantvm compvtatvr si mensvrae svnt: cvm count aeqvali 0, total / count esset $0/0$, qvod in virgvla flvitante non est error, sed valor «non nvmervs», qvem programma sine monito scriberet.

Animadvertendvm est in qvoqve ordine figvrae qvamqve variabilem significationem svam servare respectv mensvrarvm eatenvs tractatarvm: total est svmma earvm, largest maximvm earvm, dryDay indicat vtrvm nihilvm inter eas fverit. Haec proprietas, qvae post qvemqve gyrvm valet, nomen habet.