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ToUnicode function

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

To specify a handle to the keyboard layout to use to translate the specified code, use the ToUnicodeEx function.

Syntax


int WINAPI ToUnicode(
  _In_      UINT wVirtKey,
  _In_      UINT wScanCode,
  _In_opt_  const BYTE *lpKeyState,
  _Out_     LPWSTR pwszBuff,
  _In_      int cchBuff,
  _In_      UINT wFlags
);

Parameters

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, optional]

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]

Type: LPWSTR

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.

Return value

Type: int

The function returns one of the following values.

Return valueDescription
-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 pwszBuff. 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 pwszBuff.

1

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.

 

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.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Winuser.h (include Windows.h)

Library

User32.lib

DLL

User32.dll

See also

Reference
ToAscii
ToUnicodeEx
VkKeyScan
Conceptual
Keyboard Input

 

 

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