Qt QString from string - Strange letters

Question

Whenever I try to convert a std::string into a QString with this letter in it ('ß'), the QString will turn into something like "Ã" or some other really strange letters. What's wrong? I used this code and it didn't cause any errors or warnings!

std::string content = "Heißes Teil.";
ui->txtFind_lang->setText(QString::fromStdString(content));

The std::string has no problem with this character. I even wrote it into a text file without problems. So what am I doing wrong?

Answer 1

You need to set the codec to UTF-8 :

QTextCodec::setCodecForTr(QTextCodec::codecForName("UTF-8"));
QTextCodec::setCodecForCStrings(QTextCodec::codecForName("UTF-8"));
QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));

By default, Qt uses the Latin-1 encoding, which is limited. By adding this code, you set the default encoding to UTF-8 which allow you to use much more characters.

Answer 2

Though antoyo's answer works, I wasn't too sure why. So, I decided to investigate.

All of my documents are encoded in UTF-8, as are most web-pages. The ß character has the UTF code point of UTF+00DF.

Since UTF-8 is a variable length encoding, in the binary form, ß would be encoded as 11000011 10011111 or C3 9F. Since by default Qt relies on Latin1 encoding. It would read ß as two different characters. The first one C3 will map to Ã and the second one 9F will not map to anything as Latin1 does not recognize bytes in between 128-159 (in decimal).

That's why ß appears as Ã when using Latin1 encoding.

---

Side note: You might want to brush up on how UTF-8 encoding works, because otherwise it seems a little unintuitive that ß takes two bytes even though its code point DF is less than FF and should consume just one byte.