Struct declaration WLAN_AVAILABLE_NETWORK Network[1];

Question

Given this struct:

typedef struct _WLAN_AVAILABLE_NETWORK_LIST {
    WLAN_AVAILABLE_NETWORK Network[1];
} *PWLAN_AVAILABLE_NETWORK_LIST;

What does the declaration WLAN_AVAILABLE_NETWORK Network[1] mean?

It would be helpful to see what `WLAN_AVAILABLE_NETWORK` is but my first guess it is to emulate passing references without flooding code with `&`, similar to what `gmp` does. — pmr, Aug 13 '12 at 15:11
@pmr, http://msdn.microsoft.com/en-us/library/windows/desktop/ms707403(v=vs.85).aspx — chris, Aug 13 '12 at 15:12

score 9 · Accepted Answer · edited May 23 '17 at 11:48

9

It looks likely that Network is intended to serve as a flexible array member. By over-allocating the struct by sizeof(Network) * (n - 1) bytes, the library and client code can access past the end of the struct as if the array member was n elements long.

Library code:

PWLAN_AVAILABLE_NETWORK_LIST list = malloc(sizeof(_WLAN_AVAILABLE_NETWORK_LIST)
    + (sizeof(WLAN_AVAILABLE_NETWORK) * (n - 1)));
for (int i = 0; i < n; ++i) {
    list->Network[i] = ...;
}

Client code:

for (int i = 0; i < n; ++i) {
    do_something(list->Network[i]);
}

edited May 23 '17 at 11:48

Community

1
1

answered Aug 13 '12 at 15:14

ecatmur

152,476
27
293
366

1

I was about to type this. The function [WlanGetAvailableNetworkList](http://msdn.microsoft.com/en-us/library/windows/desktop/ms706749.aspx) only ever gives the caller back a pointer to the struct, which has a count of the items in the array as another member. – Matt K Aug 13 '12 at 15:16

score 1 · Answer 2 · answered Aug 13 '12 at 15:13

1

typedef struct _WLAN_AVAILABLE_NETWORK_LIST { declaring a struct named _wlan...list

WLAN_AVAILABLE_NETWORK Network[1]; assumes a struct called WLAN_AVAILABLE_NETWORK is declared somewhere. It is an array of length 1 (pointless) and called Network.

} *PWLAN_AVAILABLE_NETWORK_LIST; instantly creates a (pointer) variable of this struct called pwlan...list

answered Aug 13 '12 at 15:13

Raekye

5,081
8
49
74

yeah may be pointer variable can points to some variable memory later by allocating, and by using that array variable we can use accordingly.. thank you – david Aug 24 '12 at 10:55

Struct declaration WLAN_AVAILABLE_NETWORK Network[1];

2 Answers2