RegisterWindowMessage

2.x

The RegisterWindowMessage function defines a new window message that is guaranteed to be unique throughout the system. The returned message value can be used when calling the SendMessage or PostMessage function.

Parameters

lpsz

Points to a null-terminated string that specifies the message to be registered.

Return Value

The return value is an unsigned short integer in the range 0xC000 through 0xFFFF if the message is successfully registered. Otherwise, the return value is 0.

Comments

RegisterWindowMessage 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 Windows session ends.

Use the RegisterWindowMessage function only 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, such predefined control classes as BUTTON, EDIT, LISTBOX, and COMBOBOX may use values in this range.)

See Also

PostAppMessage, PostMessage, SendMessage