Understanding toInt() function to convert QString to int

[jefazo92]

Hi everyone,

I'm trying to convert a QString into an int. I have read the documentation (https://doc.qt.io/qt-5/qstring.html#toInt) but I don't understand the purpose of the *ok pointer in the toInt() function. What I'm trying to do is something as simple as converting QString Number = "1234" into an integer. That's all.

Any help would be greatly appreciated. Thank you.

[Kerndog73]

If ok is not nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

The ok pointer is used for error reporting.

QString str = "1234";
bool ok;
int num = str.toInt(&ok);
if (!ok) {
  // conversion failed
}

[jefazo92]

Hi @Kerndog73 ,

So basically I could do something as :

QString str = "1234";
bool ok;
int num = str.toInt(&ok);
if (!ok) {
  cout << "Conversion failed. Repeat conversion" <<endl;
}

It's just to check errors but should not affect my conversion from QString to int.

[Kerndog73]

That's right, it won't effect the conversion. It's only used for checking errors. If you're confident that the string is a valid integer then you could do str.toInt();.

[jefazo92]

Thank you @Kerndog73 , I will include it anyways as a checking tool for my program and to perform conversion again if it failed previously. :)