How to obtain high and low Windows messages

Long A = 123456789;
Take the high position. First, shift A to the right of 16 digits. Then, the high position is automatically filled with zero.
A >>= 16;
At this time, the value is zero. This value is used to store Y coordinates in the message.
For a low position, it is directly connected to 0xffff, that is
A & = 0 xFFFF;
Because the binary value of 0xffff is 1111111111111111, the low value of 0xffff is obtained. Because the high value of 0xffff is zero, it is automatically truncated.
This value is used to store the coordinates of X in the message.
Protected override void wndproc (ref message m)
{
Long H = (long) M. lparam;
Long L = (long) M. lparam;

If (M. MSG = 0x201)
{
H> = 16;

L & = 0 xFFFF;
String STR = "Y:" + H. tostring () + ", X:" + L. tostring ();
MessageBox. Show (STR );
}
Base. wndproc (ref m );
}