Structures

Note  The memory for all Microsoft DirectX?structures must be initialized to 0 before use. In addition, all structures that contain a dwSize member should set the member to the size of the structure, in bytes, before use. The following example performs these tasks on a common structure, DIDEVCAPS:

DIDEVCAPS didevcaps; // Can't use this yet

ZeroMemory(&didevcaps, sizeof(didevcaps));
didevcaps.dwSize = sizeof(didevcaps);

// Now the structure Can be used.