程序代码：

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>

int main (void)
{
    HWND                    hWnd;
    RECT                    rect;
    int                     iScreenWidth, iScreenHeight;
    int                     iStepx, iStepy;
    int                     iSpeed;

    srand ( (unsigned) GetTickCount () );
    iSpeed = rand () % 4 + 1;

    printf ("我会移动, 你说怪不怪异?\n");
    iStepx = 1;
    iStepy = 1;

    iScreenWidth = GetSystemMetrics (SM_CXSCREEN);
    iScreenHeight = GetSystemMetrics (SM_CYSCREEN);
    hWnd = GetForegroundWindow ();
    SetWindowPos (hWnd, HWND_TOPMOST, 0, 0, 100, 100, SWP_NOSIZE);
    while (1)
    {
        GetWindowRect (hWnd, &rect);
        OffsetRect (&rect, iSpeed * iStepx, iSpeed * iStepy);
        if ( rect.right >= iScreenWidth || rect.left <= 0 )
        {
            iStepx *= -1;
        }
        if ( rect.bottom >= iScreenHeight || rect.top <= 0 )
        {
            iStepy *= -1;
        }
        MoveWindow (hWnd, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, TRUE);
        Sleep (10);
    }
    return 0;
}