C++ Class or Struct compatiblity with C struct

Question

Is it possible to write a C++ class or struct that is fully compatible with C struct. From compatibility I mean size of the object and memory locations of the variables. I k

Answer 1

Use the same "struct" in both C and C++. If you want to add methods in the C++ implementation, you can inherit the struct and the size should be the same as long as you don't add data members or virtual functions.

Be aware that if you have an empty struct or data members that are empty structs, they are different sizes in C and C++. In C, sizeof(empty-struct) == 0 although in C99, empty-structs are not supposed to be allowed (but may be supported anyway as a "compiler extension"). In C++, sizeof(empty-struct) != 0 (typical value is 1).