sizeof() Operator

This operator returns the size, in bytes, of the enclosed identifier.

Syntax:

sizeof(id)

id may be either a built-in type, typedef'ed type, user-defined type or field reference. Taking the size of user-defined dynamic type is incorrect and will result in compile error.

The following code fragment illustrates the use of the sizeof() operator:

struct A
{
    int a;
    int b;
    int c[4];
};

struct B
{
    int a;
    int b[a];
};

struct C
{
    B b;

    const SizeOfInt = sizeof(int);      // correct, evaluates to 4
    const SizeOfA = sizeof(A);          // correct, evaluates to 24 (size of static user-defined type A)
    const SizeOfB = sizeof(B);          // incorrect, results in compile-time error, B is dynamic type
    var SizeOfb = sizeof(b);          // correct, will be calculated at run-time
};