未处理的异常：一个无效的参数被传递给 function，它认为无效参数在 UWP 应用程序中是致命的

Question

So I was making a polynomial simplifier for my school project. I decided to make the application using C++ UWP in Visual Studio.

As one of the extra features of the application I implemented a system to store and retrieve polynomials from a file so that you can access your previously entered polynomials. I am using boost::filesystem for this. The code compiles fine. But while debugging, this function:

fs::exists(basePath) // namespace fs = boost::filesystem

...is somehow causing the following exception:

Unhandled exception at 0x00007FFBB71AAFEC (ucrtbased.dll) in ExpressionSimplifierV4 UWP.exe: An invalid parameter was passed to a function that considers invalid parameters fatal.

..thrown from this line:

rootFrame->Navigate(TypeName(MainPage::typeid), e->Arguments); // App.xaml.cpp

My question: What is the cause of this exception and how do I resolve it ?

If any extra information is needed, do tell me... Thanks

Answer 1

When writing UWP applications, be aware that they by design run in a 'locked-down' environment. One aspect of this is that they have very limited access to the file system.

A UWP application by default has:

• read-only access to its own installed directory (which is typically the 'current working directory' at start-up). This is pointed to by Windows.ApplicationModel.Package.Current.InstalledLocation .

• read/write access to its own per user application data directory. The non-roaming version is ApplicationData.Current.LocalFolder . The roaming version is ApplicationData.Current.RoamingFolder .

• read/write access to a per user application temporary directory that may or may not be there on future invocations of the application. This is ApplicationData.Current.TemporaryFolder .

Any attempt to access a file folder other than those above by default will fail .

See Microsoft Docs .