将字符串中的所有非ASCII字符替换为其等效的ASCII

Question

Using Qt/C++, I need to generate a string with only a subset of ASCII characters : letters, digits, hyphen, underscore, period, or colon.

As input, I can have anything.

So I try to apply some rules :

• every QChar::isSpace will be replaced with an underscore
• every non-ASCII letters will be replaced with an ASCII equivalent (example : "é" will be replaced with "e")
• every other non-ASCII character will be removed

Is there any simple way with Qt/C++ to apply the 2nd and the 3rd rule ?

Thanks

Answer 1

Yes, there is a way. At first you should do unicode normalization to your string with QString::normalized . Normalization is needed to separate diacritical signs from letters and to replace some fancy symbols with ascii equivalents. Here you can read about normalization forms.

Then you may take chars which can be encoded in Latin-1. Can be tested with toLatin1 method of QChar.

char QChar::toLatin1() const

Returns the Latin-1 character equivalent to the QChar, or 0. This is mainly useful for non-internationalized software.

...

QString testString = QString::fromUtf8("Ceñía-üÏÖ马克ñ");
QString normalized = testString.normalized(QString::NormalizationForm_KD);
QString result;

copy_if(normalized.begin(), normalized.end(), back_inserter(result), [](QChar& c) {
    return c.toLatin1() != 0;
});

qDebug() << result; // Cenia-uIOn