Android .txt resource file editing in Qt

jsulm

I may be wrong but as far as I know on Android you cannot write in the directory where your app is installed (for security reasons). The qrc file is part of your application, so I guess it will not work this way. You should use a directory where your app has write access.

monster

I see. So am I able to create a blank file in the application when it starts for the first time and then to edit it when it actually exists in the given location? How should I do it?

jsulm

Check this one on Android:

QString QStandardPaths::writableLocation(StandardLocation type)
Call it like this:
QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);

More here: http://doc.qt.io/qt-5/qstandardpaths.html

monster

Thank you a LOT! Especially for Standard Paths. It works :) I've got last small question. I've noticed that I understand file operation modes wrong. Writing in append mode seems easy. As a ReadOnly mode, I understand the mode in which you start reading the file from the beggining. But now I found that WriteOnly mode erases all file and starts writing from the beginning! Is that right? I thought that WriteOnly opens the file with pointer pointing the beginning of file, and so I thought that writing in that mode allows me to replace previously written characters. I want to find the mode that allows me to change the number at the beginning without writing whole file again...

monster

Sorry that I've got even more questions :D

Can I declare structures with QStrings and then resize them inside that structure? Does structure also resize itself then?

Am I correct that I don't have to resize the QString when I declare:
QString valuvalue = somekindofcharorstring;
?
It changes its size automatically, am I right?

stackprogramer

hi,i offer, you can use xml or json for saving your data
Data storage

monster

I'm afraid that it is too big amount of knowledge for such a small project, but I will consider it, thank you :)

kornava

I think it can be much easier with LocalStorage , it can be done entirely from QML:
http://qmlbook.github.io/en/ch12/index.html#local-storage-sql

I think this is the simpler solution to establish saving ability for an app, but you can't access the stored information from outside your app.

jsulm

@monster Use

QIODevice::WriteOnly | QIODevice::Append

Then the file should not be overwritten.

You can declare structures containing strings. The size of the struct does not depend on the size of stored strings, because internally QString stores the actual string on the heap and just points to it. On my machine sizeof(StrStruct) is 16 (StrStruct contains two QString members). So it is 2 * sizeof(void*).

monster

Thank you all. Everything works fine. I just corrected my old, first example. There were many problems. I can upload example that works, and correctly fills and reads file according to the picked scheme if anybody is interested.