so i want to build with blueprints and code with c++, can i mix them in a game together, if i can please tell me how, Thank you!
Yes you can, basically the UE uses the same method, for example, the character is basically C++ code but we use it as Blueprint or write our code in C++ and use it directly in Blueprints
this image show how make a Blueprint from C++ code
It’s not matter of “compatible” 
it simply project has C++ code or not and that it, technically there no blueprint or C++ project
Everything in Unreal 4 is C++ but many parts of it can be accessed in Blueprints so that you don’t have to use C++ for those things if you don’t want to.
Sometimes there are things I cannot access in Blueprints, so I add some more C++ to my project that makes those things accessible in Blueprints, or I just do it in C++ if I don’t need blueprint nodes and properties for them.