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Editorial Team
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Asked: 2026-05-21T03:16:13+00:00

I’m trying to display Chinese characters encoded in UTF-8 in a PlainTextEdit control, but

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I’m trying to display Chinese characters encoded in UTF-8 in a PlainTextEdit control, but it doesn’t render them properly.

My data comes from a database and I know that the string I get in Qt is correct (the bytes are the same as in the database). Once I have the Chinese character in a QString, I tried various things to display it but always results in either question marks or random ASCII characters:

QString chineseChar = query.value(fieldNo).toString(); // get the character

ui->plainTextEdit->appendPlainText(chineseChar); // doesn't work
ui->plainTextEdit->appendPlainText(chineseChar.toUtf8()); // doesn't work
ui->plainTextEdit->appendPlainText(QString::fromUtf8(chineseChar.toAscii()); // doesn't work

Any suggestion on how to handle that?

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1 Answer

  1. Editorial Team

    “My data comes from a database and I know that the string I get in Qt is correct (the bytes are the same as in the database).”

    How did you check that? Try with chineseChar.toUtf8().toHex().

    Once your string data is in a QString, all UI elements accepting a QString will handle it correctly. Usually the error happens when converting from plain text data(const char*/QByteArray) to the QString.
    The conversions here:

    ui->plainTextEdit->appendPlainText(chineseChar.toUtf8()); // doesn't work
ui->plainTextEdit->appendPlainText(QString::fromUtf8(chineseChar.toAscii()); // doesn't work

    convert the unicode string to a bytearray, and then implicitely back to a QString, as those methods expect a QString.
    I suggest you define QT_NO_CAST_FROM_ASCII and QT_NO_CAST_TO_ASCII to avoid any unwanted QByteArray<->QString conversions.

    If the string is wrong, the error usually happened before, when converting from QByteArray/const char* to QString, i.e. in query.value(fieldNo).toString(). Try with:

     QString chineseChar = QString::fromUtf8( query.value(fieldNo).toByteArray() );

    If that doesn’t help, the problem is somewhere in QtSQL assuming the wrong encoding for the data it receives from the database.

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