error C4996: 'scanf': This function or variable may be unsafe in c programming

Another way is when you create a new project, you don't click to Security Development Lifecycle (SDL) checks:

Or if you are in a project: Right-click your project->Properties->Configuration Properties->C/C++ ->All Options>Sroll your mouse and find SDL checks, you edit it to NO(/sdl-), then Apply, OK

You can add "_CRT_SECURE_NO_WARNINGS" in Preprocessor Definitions.

Right-click your project->Properties->Configuration Properties->C/C++ ->Preprocessor->Preprocessor Definitions.

Another way to suppress the error: Add this line at the top in C/C++ file:

#define _CRT_SECURE_NO_WARNINGS

It sounds like it's just a compiler warning.

Usage of scanf_s prevents possible buffer overflow.
See: http://code.wikia.com/wiki/Scanf_s

Good explanation as to why scanf can be dangerous: Disadvantages of scanf

So as suggested, you can try replacing scanf with scanf_s or disable the compiler warning.