QLists with signed int instead of unsigned int?

[Alex-Krieg]

Why does QT use signed int for indexing an QList or other form of listed object?

QList<double> list;
int index = 0;

list[index]  = 1.05;

Arrays always start at Index 0, therefore I can't see any reason, why signed int is used.
The same applies for the return value of member functions like:

list.size();

The list can't be smaller than 0.

Is there any logical reason of taking signed values?
I have to convert them everywhere, because I use always unsigned values for things which can't handle negative numbers.

Thanks for your answer
Alex

[Christian Ehrlicher]

Is there any logical reason of taking signed values?

Yes, e.g. to be able to return -1 on error.
Why do you think you need it? Are you sure you have (more than) 4GB of contiguous memory?
You can take a look at the devel mailing list archives - this question is discussed there now and then.

[Pl45m4]

@Alex-Krieg

Another example:
IDs of QButtonGroup start at -2 and decrease for every new button added to this group (default behavior).
-1 is to auto-assign an ID. User-defined IDs should start at 0 (increasing).

https://doc.qt.io/qt-5/qbuttongroup.html#addButton

So there are some cases where the sign matters.
(In addition to the -1 which is returned e.g. as error code)

[mrjj]

Hi
Even if the other already explained it...
Think of it as a role. The role of being an index type.
We need sometimes to flag the index as invalid.
And since none ever uses negative indexes, using signed can be used for that.