RegisterWindowMessageA function

Defines a new window message that is guaranteed to be unique throughout the system. The message value can be used when sending or posting messages.

Syntax

UINT RegisterWindowMessageA(
  LPCSTR lpString
);

Parameters

lpString

Type: LPCTSTR

The message to be registered.

Return Value

Type: Type: UINT

If the message is successfully registered, the return value is a message identifier in the range 0xC000 through 0xFFFF.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

The RegisterWindowMessage function is typically used to register messages for communicating between two cooperating applications.

If two different applications register the same message string, the applications return the same message value. The message remains registered until the session ends.

Only use RegisterWindowMessage when more than one application must process the same message. For sending private messages within a window class, an application can use any integer in the range WM_USER through 0x7FFF. (Messages in this range are private to a window class, not to an application. For example, predefined control classes such as BUTTON, EDIT, LISTBOX, and COMBOBOX may use values in this range.)

Examples

For an example, see Finding Text.

Requirements

   
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header winuser.h (include Windows.h)
Library User32.lib
DLL User32.dll

See Also

Conceptual

Messages and Message Queues

PostMessage

Reference

SendMessage