Sometimes when I build a Qt C++ app (MinGW) and open it with arguments in Windows 10, it shows Unicode arguments as question marks. I don't really know when but I think it depends on parameter's length and being or not being whitespaces in parameter.

For example (demonstration):

( chcp 65001 )
 

>app.exe سلام

receives: سلام

>app.exe سلاممممم

receives: سلاممممم

>app.exe سلامممممم

receives: ?????????

>app.exe d:\خطا

receives: d:???

>app.exe "d:\خطا دار"

receives: d:\خطا دار

>app.exe C:\Users\Reza\Desktop\خطا.txt

receives: C:\Users\Reza\Desktop???.txt

>app.exe C:\Users\Default\Desktop\خطا.txt

receives: C:\Users\Default\Desktop\خطا.txt

I tested using QCommandLineParser, and also app.arguments() but all were the same.

Even I checked values stored in argv[] manually and even there, some Unicode characters where stored as question marks.