Question

What is the use of defining a anonymous structure within a structure? When should this concept be used?

Answer 1

I sometimes use it to create a union between some data:

typedef union {
    struct {
        int x, y, z;
    };
    int elements[3];
} Point;

This way I can easily loop over the coordinates with elements but also use the shorter form x, y and z instead of elements[0] etc.