&,引用,获得ioffset的地址,
LPARAM A 32-bit value passed as a parameter to a window procedure or callback function.
UINT = unsigned int,无符号整型
LPARAM A 32-bit value passed as a parameter to a window procedure or callback function.
UINT = unsigned int,无符号整型
LPARAM 定义为 unsigned long //32bit&ioffset: 取 ioffset 的地址, &ioffset 是 int* 类型,
(LPARAM)&ioffset, 将 int* 强制转换为 LPARAM 类型。