ToUnicode

The ToUnicode function translates the specified virtual-key code and keyboard state to the corresponding Unicode character or characters. 

int ToUnicode(
  UINT wVirtKey,    // virtual-key code
  UINT wScanCode,   // scan code
  PBYTE lpKeyState, // address of key-state array
  LPWSTR pwszBuff,  // buffer for translated key
  int cchBuff,      // size of translated key buffer
  UINT wFlags       // set of function-conditioning flags
);

Parameters

wVirtKey
Specifies the virtual-key code to be translated.
wScanCode
Specifies 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
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
Pointer to the buffer that receives the translated Unicode character or characters.
cchBuff
Specifies the size in characters of the buffer pointed to by the pwszBuff parameter.
wFlags
A set of bit flags that condition the behavior of the function. Set bit 0 if a menu is active. Bits 1 through 31 are reserved.

Return Values

The function returns one of the following values.

Value Meaning
– 1 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 pwszBuffer. For example, the function writes the character SPACING ACUTE (0x00B4), rather than the character NON_SPACING ACUTE (0x0301).
0 The specified virtual key has no translation for the current state of the keyboard. Nothing was written to the buffer specified by pwszBuffer.
1 One character was written to the buffer specified by pwszBuffer.
2 or more 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.

Remarks

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

Typically, ToUnicode 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.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Unsupported.
  Windows CE: Unsupported.
  Header: Declared in winuser.h.
  Import Library: Use user32.lib.

See Also

Keyboard Input Overview, Keyboard Input Functions, ToAscii, VkKeyScan