That you can read and write from different elements in a union if the elements are structs and have the same prefix structure:

union {
   struct {int x, y; };
   struct {int u, v; };
}

x = 45;
cout << u;

I also like that the library and language is designed in such a way that the compilers can optimize usage of the library really well; gcc can optimize through almost everything in there.

structures declared within an anonymous union are not legal C++. Its a visual studio extension.

-changed wording slightly

That you can read and write from different elements in a union if the elements are structs and have the same prefix structure:

union {
   struct {int x, y; };
   struct {int u, v; };
}

x = 45;
cout << u;

I also like that the library and language is designed in such a way that the compilers can optimize usage of the library really well; gcc can optimize through almost everything in there.

structures declared within an anonymous union are not legal C++. Its a visual studio extension.

That you can read and write from different elements in a union if the elements are structs and have the same prefix structure:

union {
   struct {int x, y; };
   struct {int u, v; };
}

x = 45;
cout << u;

I also like that the library and language is designed in such a way that the compilers can optimize usage of the library really well; gcc can optimize through almost everything in there.

anonymous structures within an anonymous union are not legal C++. Its a visual studio extension.

That you can read and write from different elements in a union if the elements are structs and have the same prefix structure:

union {
   struct {int x, y; };
   struct {int u, v; };
}

x = 45;
cout << u;

I also like that the library and language is designed in such a way that the compilers can optimize usage of the library really well; gcc can optimize through almost everything in there.

anonymous structures within an union are not legal C++. Its a visual studio extension.