请问delphi中的超链接问题：

下面的是我查到的格式：
ShellExecute(handle,nil,pchar('http//www.buyman.com/'),nil,nil,sw_shownormal);
{ 如果为字符串参数,其中包含有变量或运算的需要用 PCHAR() 函数进行类型转化。 }
但是我不明白“handle”，“Nil”，“sw_shownormal”这些参数倒底传递的是什么？

另外：关于这些问题我可以在Delphi自带的帮助里面查到吗？
我现在只会用帮助查找某些控件的属性，方法啊什么的～～！！

可用MSDN或者PDK查询。另外安装的。

ShellExecute Function

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Performs an operation on a specified file.

Syntax

HINSTANCE ShellExecute( HWND hwnd,
LPCTSTR lpOperation,
LPCTSTR lpFile,
LPCTSTR lpParameters,
LPCTSTR lpDirectory,
INT nShowCmd
);
Parameters

hwnd
[in] Handle to a parent window. This window receives any message boxes that an application produces, such as error reporting.
lpOperation
[in] Pointer to a null-terminated string, referred to in this case as a verb, that specifies the action to be performed. The set of available verbs depends on the particular file or folder. Generally, the actions available from an object's shortcut menu are available verbs. For more information about verbs and their availability, see Object Verbs. See Extending Shortcut Menus for further discussion of shortcut menus. The following verbs are commonly used.
edit
Launches an editor and opens the document for editing. If lpFile is not a document file, the function will fail.
explore
Explores the folder specified by lpFile.
find
Initiates a search starting from the specified directory.
open
Opens the file specified by the lpFile parameter. The file can be an executable file, a document file, or a folder.
print
Prints the document file specified by lpFile. If lpFile is not a document file, the function will fail.
NULL
For systems prior to Microsoft Windows 2000, the default verb is used if it is valid and available in the registry. If not, the "open" verb is used.

For Windows 2000 and later systems, the default verb is used if available. If not, the "open" verb is used. If neither verb is available, the system uses the first verb listed in the registry.

lpFile
[in] Pointer to a null-terminated string that specifies the file or object on which to execute the specified verb. To specify a Shell namespace object, pass the fully qualified parse name. Note that not all verbs are supported on all objects. For example, not all document types support the "print" verb.
lpParameters
[in] If the lpFile parameter specifies an executable file, lpParameters is a pointer to a null-terminated string that specifies the parameters to be passed to the application. The format of this string is determined by the verb that is to be invoked. If lpFile specifies a document file, lpParameters should be NULL.
lpDirectory
[in] Pointer to a null-terminated string that specifies the default directory.
nShowCmd
[in] Flags that specify how an application is to be displayed when it is opened. If lpFile specifies a document file, the flag is simply passed to the associated application. It is up to the application to decide how to handle it.
SW_HIDE
Hides the window and activates another window.
SW_MAXIMIZE
Maximizes the specified window.
SW_MINIMIZE
Minimizes the specified window and activates the next top-level window in the z-order.
SW_RESTORE
Activates and displays the window. If the window is minimized or maximized, Windows restores it to its original size and position. An application should specify this flag when restoring a minimized window.
SW_SHOW
Activates the window and displays it in its current size and position.
SW_SHOWDEFAULT
Sets the show state based on the SW_ flag specified in the STARTUPINFO structure passed to the CreateProcess function by the program that started the application. An application should call ShowWindow with this flag to set the initial show state of its main window.
SW_SHOWMAXIMIZED
Activates the window and displays it as a maximized window.
SW_SHOWMINIMIZED
Activates the window and displays it as a minimized window.
SW_SHOWMINNOACTIVE
Displays the window as a minimized window. The active window remains active.
SW_SHOWNA
Displays the window in its current state. The active window remains active.
SW_SHOWNOACTIVATE
Displays a window in its most recent size and position. The active window remains active.
SW_SHOWNORMAL
Activates and displays a window. If the window is minimized or maximized, Windows restores it to its original size and position. An application should specify this flag when displaying the window for the first time.
Return Value

Returns a value greater than 32 if successful, or an error value that is less than or equal to 32 otherwise. The following table lists the error values. The return value is cast as an HINSTANCE for backward compatibility with 16-bit Windows applications. It is not a true HINSTANCE, however. The only thing that can be done with the returned HINSTANCE is to cast it to an int and compare it with the value 32 or one of the error codes below.

0 The operating system is out of memory or resources.
ERROR_FILE_NOT_FOUND The specified file was not found.
ERROR_PATH_NOT_FOUND The specified path was not found.
ERROR_BAD_FORMAT The .exe file is invalid (non-Microsoft Win32 .exe or error in .exe image).
SE_ERR_ACCESSDENIED The operating system denied access to the specified file.
SE_ERR_ASSOCINCOMPLETE The file name association is incomplete or invalid.
SE_ERR_DDEBUSY The Dynamic Data Exchange (DDE) transaction could not be completed because other DDE transactions were being processed.
SE_ERR_DDEFAIL The DDE transaction failed.
SE_ERR_DDETIMEOUT The DDE transaction could not be completed because the request timed out.
SE_ERR_DLLNOTFOUND The specified dynamic-link library (DLL) was not found.
SE_ERR_FNF The specified file was not found.
SE_ERR_NOASSOC There is no application associated with the given file name extension. This error will also be returned if you attempt to print a file that is not printable.
SE_ERR_OOM There was not enough memory to complete the operation.
SE_ERR_PNF The specified path was not found.
SE_ERR_SHARE A sharing violation occurred.

Remarks

This method allows you to execute any commands in a folder's shortcut menu or stored in the registry.

To open a folder, use either of the following calls:

ShellExecute(handle, NULL, <fully_qualified_path_to_folder>, NULL, NULL, SW_SHOWNORMAL);

or

ShellExecute(handle, "open", <fully_qualified_path_to_folder>, NULL, NULL, SW_SHOWNORMAL);

To explore a folder, use:

ShellExecute(handle, "explore", <fully_qualified_path_to_folder>, NULL, NULL, SW_SHOWNORMAL);

To launch the Shell's Find utility for a directory, use:

ShellExecute(handle, "find", <fully_qualified_path_to_folder>, NULL, NULL, 0);

If lpOperation is NULL, the function opens the file specified by lpFile. If lpOperation is "open" or "explore", the function attempts to open or explore the folder.

To obtain information about the application that is launched as a result of calling ShellExecute, use ShellExecuteEx.

Note The Launch folder windows in a separate process setting in Folder Options affects ShellExecute. If that option is disabled (the default setting), ShellExecute uses an open Explorer window rather than launch a new one. If no Explorer window is open, ShellExecute launches a new one.
Windows 95/98/Me: ShellExecute is supported by the Microsoft Layer for Unicode. To use this, you must add certain files to your application, as outlined in Microsoft Layer for Unicode on Windows 95/98/Me Systems.

Function Information

Minimum DLL Version shell32.dll version 3.51 or later
Custom Implementation No
Header shellapi.h
Import library shell32.lib
Minimum operating systems Windows NT 3.1, Windows 95
Unicode Implemented as ANSI and Unicode versions.

See Also

IShellExecuteHook