MSDN Documentation

TranslateMessage function

Header: Winuser.h

Library: User32.lib

DLL: User32.dll

Synopsis

BOOL TranslateMessage(
    const MSG *lpMsg
);

Parameters

Return value

If the function succeeds, the return value is nonzero.

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

Note that TranslateMessage always returns TRUE if the message is not a keyboard message.

Remarks

• Used primarily to translate virtual-key messages (WM_KEYDOWN, WM_KEYUP) into character messages (WM_CHAR).
• It does not modify the message itself; instead, it may post a WM_CHAR message to the thread's message queue.
• Typical usage in a message loop:

  while (GetMessage(&msg, NULL, 0, 0)) {
      TranslateMessage(&msg);
      DispatchMessage(&msg);
  }

• Do not call TranslateMessage for messages that are not keyboard messages.

Example

#include <windows.h>

LRESULT CALLBACK WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
        case WM_CHAR:
            // Echo the typed character
            {
                wchar_t c = (wchar_t)wParam;
                OutputDebugStringW(&c);
            }
            return 0;
        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

int WINAPI wWinMain(HINSTANCE hInst, HINSTANCE, PWSTR, int)
{
    const wchar_t CLASS_NAME[] = L"SampleWindow";

    WNDCLASS wc = {0};
    wc.lpfnWndProc   = WndProc;
    wc.hInstance     = hInst;
    wc.lpszClassName = CLASS_NAME;
    RegisterClass(&wc);

    HWND hwnd = CreateWindowEx(
        0, CLASS_NAME, L"TranslateMessage Demo",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 500, 300,
        NULL, NULL, hInst, NULL);

    ShowWindow(hwnd, SW_SHOWDEFAULT);

    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}