C++QT5: UTF-8, QString, QByteArray, *char and Russian characters. How to change element in *char array?

Question

Qt

There is a QString in UTF-8, I need to get an *char array from it, I do this:

QString word = "Слово";
QByteArray ar = word.toUtf8();
char* FirstArray = ar.data();
FirstArray[0] = 'X';
QString word1 = QString::fromUtf8(ar.data());

And word1 becomes equal to Xword, not Xword. How to fix?

Answer 1

In UTF-8 encoding, one character is one to four bytes. Humble yourself, and if you want to change the Russian letter (2 bytes) to English (1 byte), it is better to work in UTF-16 encoding.

word1 = word;
word1[0] = 'X';

or

word1 = QString::fromUtf8(ar.data());
word1[0] = 'X';

And if there is no way, then parse UTF-8, of course.
In general, multibyte encodings are inconvenient for such operations.