sizeof() applied to structure and variable

Question

consider the following snippet:

struct foo {
  int a;
  int b;
  int c;
};

struct foo f;
printf("%u, %u\n", sizeof(struct foo), sizeof(f));

The code returns the same values, but I was wondering if sizeof() applied to variable is correct or this is just coincidence?

Thanks.

Answer 1

Both will and should indeed return the same value.

From MSDN:

The sizeof Operator
The sizeof operator gives the amount of storage, in bytes, required to store an object of the type of the operand. This operator allows you to avoid specifying machine-dependent data sizes in your programs.

sizeof unary-expression  
sizeof ( type-name )