指针而不是结构体名称的含义是什么？

Question

What does *rooms[10] mean in this code? isn't it usually struct Room ? What does it mean in this case?

struct Room
{
     float width;
     float length;
     float height;
     char *name;
};

struct House
{
     char* address;
     struct Room *rooms[10];
};

Answer 1

struct Room *rooms[10];

Per cdecl.org :

declare rooms as array 10 of pointer to struct Room

This would be used when a House may contain up to 10 Rooms, each of which are allocated elsewhere, using null pointers to represent "unused" slots in the array.

Answer 2

In

struct House
{
     char* address;
     struct Room rooms[10];
};

you have 10 full instances of a Room . That is your House structure size is 10 times the size of the Room structure plus some extra (for the address ). Also, all 10 of these are in nearby locations in memory, causing higher fragmentation.

On the other hand, in

struct House
{
     char* address;
     struct Room *rooms[10];
};

you only have to store pointers to 10 rooms (which need to be allocated on the heap). In the first case when you call a function with House as parameter your stack is blown up because it needs a huge structure to be stored there while on the second case a much smaller structure is copied, resulting in faster function calls.