copy derived structure, is it legal c++ code?

[FFMG]

Hi,

I am trying to copy some variables from a struct to a derived struct.
If I have something like,

....
struct STRUCTA
{
int numA;
long numB;
float numC;
}

struct STRUCTB public STRUCTA
{
int numD;
}
....

STRUCTA structA = {0,1,2};
STRUCTB structB;
memcpy( &structB, &structA, sizeof( STRUCTA) );

....
//
Is the above code legal to copy the structure from structA to structB

Thanks

F.