/*
 * ShowWindow() Commands
 */
#define SW_HIDE             0
#define SW_SHOWNORMAL       1
#define SW_NORMAL           1
#define SW_SHOWMINIMIZED    2
#define SW_SHOWMAXIMIZED    3
#define SW_MAXIMIZE         3
#define SW_SHOWNOACTIVATE   4
#define SW_SHOW             5
#define SW_MINIMIZE         6
#define SW_SHOWMINNOACTIVE  7
#define SW_SHOWNA           8
#define SW_RESTORE          9
#define SW_SHOWDEFAULT      10
#define SW_FORCEMINIMIZE    11
#define SW_MAX              11

你传int就可以了.这个SW_HIDE是宏

补充:VC6.0里面,输入SW_HIDE,然后右键->Go To Definition Of SW_HIDE

或者安装MSDN

ShowWindow
This function sets the specified window’s show state.

BOOL ShowWindow(
HWND hWnd,
int nCmdShow );
Parameters
hWnd
Handle to the window.
nCmdShow
Specifies how the window is to be shown. The first time ShowWindow is called, the value should be the value obtained by the WinMain function in its nCmdShow parameter. In subsequent calls, this parameter can be one of the following values:
Value Description
SW_FORCEMINIMIZE Windows NT 5.0 and later: Minimizes a window, even if the thread that owns the window is hung. This flag should only be used when minimizing windows from a different thread.
SW_HIDE Hides the window and activates another window.
SW_SHOW Activates the window and displays it in its current size and position.  
SW_SHOWNA Displays the window in its current state. The active window remains active.
SW_SHOWNORMAL Activates and displays a window. If the window is minimized or maximized, the system restores it to its original size and position. An application should specify this flag when displaying the window for the first time.




Return Values
Nonzero indicates that the window was previously visible. Zero indicates that the window was previously hidden.