ToUnicodeEx function

Translates the specified virtual-key code and keyboard state to the corresponding Unicode character or characters.


int WINAPI ToUnicodeEx(
  _In_           UINT   wVirtKey,
  _In_           UINT   wScanCode,
  _In_     const BYTE   *lpKeyState,
  _Out_          LPWSTR pwszBuff,
  _In_           int    cchBuff,
  _In_           UINT   wFlags,
  _In_opt_       HKL    dwhkl


wVirtKey [in]

Type: UINT

The virtual-key code to be translated. See Virtual-Key Codes.

wScanCode [in]

Type: UINT

The hardware scan code of the key to be translated. The high-order bit of this value is set if the key is up.

lpKeyState [in]

Type: const BYTE*

A pointer to a 256-byte array that contains the current keyboard state. Each element (byte) in the array contains the state of one key. If the high-order bit of a byte is set, the key is down.

pwszBuff [out]


The buffer that receives the translated Unicode character or characters. However, this buffer may be returned without being null-terminated even though the variable name suggests that it is null-terminated.

cchBuff [in]

Type: int

The size, in characters, of the buffer pointed to by the pwszBuff parameter.

wFlags [in]

Type: UINT

The behavior of the function. If bit 0 is set, a menu is active. Bits 1 through 31 are reserved.

dwhkl [in, optional]

Type: HKL

The input locale identifier used to translate the specified code. This parameter can be any input locale identifier previously returned by the LoadKeyboardLayout function.

Return value

Type: int

The function returns one of the following values.

Return valueDescription

The specified virtual key is a dead-key character (accent or diacritic). This value is returned regardless of the keyboard layout, even if several characters have been typed and are stored in the keyboard state. If possible, even with Unicode keyboard layouts, the function has written a spacing version of the dead-key character to the buffer specified by pwszBuff. For example, the function writes the character SPACING ACUTE (0x00B4), rather than the character NON_SPACING ACUTE (0x0301).


The specified virtual key has no translation for the current state of the keyboard. Nothing was written to the buffer specified by pwszBuff.


One character was written to the buffer specified by pwszBuff.

2 ≤ value

Two or more characters were written to the buffer specified by pwszBuff. The most common cause for this is that a dead-key character (accent or diacritic) stored in the keyboard layout could not be combined with the specified virtual key to form a single character. However, the buffer may contain more characters than the return value specifies. When this happens, any extra characters are invalid and should be ignored.



The input locale identifier is a broader concept than a keyboard layout, since it can also encompass a speech-to-text converter, an Input Method Editor (IME), or any other form of input.

The parameters supplied to the ToUnicodeEx function might not be sufficient to translate the virtual-key code because a previous dead key is stored in the keyboard layout.

Typically, ToUnicodeEx performs the translation based on the virtual-key code. In some cases, however, bit 15 of the wScanCode parameter can be used to distinguish between a key press and a key release.

As ToUnicodeEx translates the virtual-key code, it also changes the state of the kernel-mode keyboard buffer. This state-change affects dead keys, ligatures, alt+numpad key entry, and so on. It might also cause undesired side-effects if used in conjunction with TranslateMessage (which also changes the state of the kernel-mode keyboard buffer).


Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]


Winuser.h (include Windows.h)





See also

Keyboard Input