ToUnicodeEx function (winuser.h)

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


int ToUnicodeEx(
  [in]           UINT       wVirtKey,
  [in]           UINT       wScanCode,
  [in]           const BYTE *lpKeyState,
  [out]          LPWSTR     pwszBuff,
  [in]           int        cchBuff,
  [in]           UINT       wFlags,
  [in, optional] HKL        dwhkl


[in] wVirtKey

Type: UINT

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

[in] wScanCode

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.

[in] lpKeyState

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. The low bit, if set, indicates that the key is toggled on. In this function, only the toggle bit of the CAPS LOCK key is relevant. The toggle state of the NUM LOCK and SCROLL LOCK keys is ignored. See GetKeyboardState for more info.

[out] pwszBuff


The buffer that receives the translated character or characters as array of UTF-16 code units. This buffer may be returned without being null-terminated even though the variable name suggests that it is null-terminated. You can use the return value of this method to determine how many characters were written.

[in] cchBuff

Type: int

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

[in] wFlags

Type: UINT

The behavior of the function.

If bit 0 is set, a menu is active. In this mode Alt+Numeric keypad key combinations are not handled.

If bit 1 is set, ToUnicodeEx will translate scancodes marked as key break events in addition to its usual treatment of key make events.

If bit 2 is set, keyboard state is not changed (Windows 10, version 1607 and newer)

All other bits (through 31) are reserved.

[in, optional] dwhkl

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 value Description
value < 0
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 ACUTE ACCENT (U+00B4), rather than the character COMBINING ACUTE ACCENT (U+0301).
The specified virtual key has no translation for the current state of the keyboard. Nothing was written to the buffer specified by pwszBuff.
value > 0
One or more UTF-16 code units were written to the buffer specified by pwszBuff. Returned pwszBuff 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.

Some keyboard layouts may return several characters and/or supplementary characters as surrogate pairs in pwszBuff. If 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 then the previous entered dead character can be combined with the current character.

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 (for example for ALT+numpad key entry).

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+Numeric keypad 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).


Requirement Value
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


Keyboard Input