如何在 C++ 或 Qt 中获取所有货币符号和货币缩写的数组？

Question

I need to get all possible currency symbols and currency abbreviations in my program in an array. How can I achieve this with C++ or possibly with Qt?

Answer 1

Parse Existing Up-To-Date Currencies List

I found the currency codes JSON list https://gist.github.com/Fluidbyte/2973986 .
This list is regularly updated.

How the list could be parsed. Download the raw JSON text from the link. Save it to an UTF-8 encoded text file. Parse it somehow about written below.

#include <QtWidgets/QApplication>    
#include <QVariantMap>
#include <QStringList>
#include <QJsonDocument>
#include <QJsonObject>
#include <QFile>
#include <QDebug>
#include <QPlainTextEdit>

using CurrencyMap = QMap<QString, QVariantMap>; // Use three-letter code as a key
using CurrencyMapIterator = QMapIterator<QString, QVariantMap>;

CurrencyMap parseCurrencyDataFromJson(QByteArray utf8Json)
{
    CurrencyMap ret;

    QJsonParseError parseError;
    QJsonDocument document = QJsonDocument::fromJson(utf8Json, &parseError);

    if (parseError.error != QJsonParseError::NoError)
    {
        qWarning() << parseError.errorString();
    }

    if (!document.isNull())
    {
        QJsonObject jobject = document.object();

        // Iterate over all the currencies
        for (QJsonValue val : jobject)
        {
            // Object of a given currency
            QJsonObject obj = val.toObject();

            // Three-letter code of the currency
            QString name = obj.value("code").toString();

            // All the data available for the given currency
            QVariantMap fields = obj.toVariantMap();

            ret.insert(name, fields);
        }
    }

    return ret;
}

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QPlainTextEdit plainTextEdit;
    plainTextEdit.show();

    // File saved from the GitHub repo
    QFile file("curr.json");
    if (file.open(QIODevice::ReadOnly))
    {
        QByteArray jsonData = file.readAll();

        CurrencyMap currencyMap = parseCurrencyDataFromJson(jsonData);

        // Output all the available currency symbols to the plainTextEdit
        CurrencyMapIterator currency(currencyMap);

        while (currency.hasNext())
        {
            currency.next();

            QString code = currency.key();
            QVariantMap fileds = currency.value();

            QStringList currencyInfo
            {
                code,
                fileds.value("symbol").toString(),
                fileds.value("symbol_native").toString()
            };

            plainTextEdit.appendPlainText(currencyInfo.join('\t'));
        }

        QString total = QString("\nTotal Available Currencies Count = %1")
            .arg(currencyMap.count());

        plainTextEdit.appendPlainText(total);
    }

    return a.exec();
}

---

QChar-Limited Solution

QChar and Unicode based solution. But be note that QChar itself supports codes up to 0xFFFF maximum only. Therefore only limited amount of symbols can be retrieved this way.

// In Qt, Unicode characters are 16-bit entities.
// QChar itself supports only codes with 0xFFFF maximum
QList<QChar> getAllUnicodeSymbolsForCategory(QChar::Category cat)
{
    QList<QChar> ret;

    // QChar actually stores 16-bit values
    const static quint16 QCharMaximum = 0xFFFF;

    for (quint16 val = 0; val < QCharMaximum; val++)
    {
        QChar ch(val);

        if (ch.category() == cat)
        {
            ret.append(ch);
        }
    }

    return ret; 
}

Usage

QList<QChar> currencies = getAllUnicodeSymbolsForCategory(QChar::Symbol_Currency);