Question

I have structure(A) and it takes another structure(B) as member.
Now i want structure C as member of A instead of B.
Both B and C are of same type

typedef struct
{
 int a;
 B b;
}A

typedef struct
{
 int a;
}B

typedef struct
{
 int a;
}C

How can i assign struct C as member instead of B. How to do typecasting
Please help

Answer 1

Without knowing why you want to do this, its hard to recommend a strategy. Here are a few options though.

Option 1: Use Templates. (C++ only)

template <type T>
struct A
{
  int a;
  T* t;
};

struct Foo
{
  int a;
};

struct B : public Foo
{
};

struct C : public Foo
{
};

struct A<Foo> A_foo;

struct B;
struct C;

A_foo.t = &B; //OK! This can now take pointer to any class that extends Foo.
A_foo.t = &C; //OK!

Option 2: Make struct A contain a void* (not recommended, you will lose all type safety). (Both C/C++)

struct A 
{
  int a;
  void* foo; // you can now assign any pointer to foo :-S
};