"runtime visual c++" error on a Qt project not using (at least directly) visual c++, is this even legal?

Question

Qt

kuta widgets are used, can they use visual c++?

Answer 1

Qt is a collection of libraries. To compile a project using qt under windows, you need either mingw or microsoft visual studio.
In your code, the run-time error is most likely due to an attempt to get data beyond the bounds of the array, or reading data from a null pointer. Run in debug mode and look for the error.