When reading QJsonArray it gives always 0

JonB

I don't know where @suslucoder gets his JSON from. And I admit in my code I save/restore integers (C++ type) not floating point. But for integers at least I note that Qt JSON saves as a number, not as a string. So I imagine it would save a floating point similarly. Just saying.

deleted286

@JonB ı didnt get my json from anywhere. I create it by myself

deleted286

@sierdzio I did it like this way. But it cant read some datas still. What should be the reason? It reads the first and last element of 1 array. And then, didnt read the second item of an array. Read the 4.element of array 2. I didnt understand

Christian Ehrlicher

Since you created the json manually you're mixing . and ,. Use the proper json notation for doubles without quotes if you want that someone else will be able to read them and don't create such files manually.

deleted286

@Christian-Ehrlicher I have LineEdit. I take datas from line edit on my qui, and save those datas in txt file which is formatted json. I want to take float or double nums on line edit.

I have " " because line edit accept strings.

Pl45m4

@suslucoder said in When reading QJsonArray it gives always 0:

I have " " because line edit accept strings.

But you cant save strings in the same way as you save floats / doubles ~~or ints~~ (edit: No ints).

@Christian-Ehrlicher said in When reading QJsonArray it gives always 0:

It's not 5.0 but "5.0" and this is a string. See also QJsonValue::Type()

That's what @Christian-Ehrlicher said here

So you have to differentiate what is going to be stored in your Json.
(If you build your Json yourself -> strings with "....." and floats with . as separator to avoid read errors)

You can save everything as string, but then you have to convert it when reading the values again (-> also works best when using a dot as separator. Not every locale supports , as decimal separator. This is why you probably got 0)

JonB

@suslucoder
...Which is why I suggested you might choose to save/put in file 41.123 instead of string with quotes like your "41,123", then you will be storing a number and won't have to convert from a string....

Christian Ehrlicher

Or use a proper QDoubleSpinbox

Pl45m4

Or a QLineEdit with an input mask, so you can be sure that is input of this widget gonna be a number. Then you can write it as double to your Json.

https://doc.qt.io/qt-5/qlineedit.html#inputMask-prop

JonB

@suslucoder said in When reading QJsonArray it gives always 0:

ı didnt get my json from anywhere. I create it by myself

So this is not a widget issue, at least at this stage. It's a question of OP deciding on a type to be used in the JSON.

sierdzio

Exactly. You should format the data properly when you save it. Then the whole problem will just go away and a plain toDouble() will work when reading the file.

deleted286

Thanks for all answers. I will reformat my json file and try it again