ToAscii function

Translates the specified virtual-key code and keyboard state to the corresponding character or characters. The function translates the code using the input language and physical keyboard layout identified by the keyboard layout handle.

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

Syntax


int WINAPI ToAscii(
  _In_      UINT uVirtKey,
  _In_      UINT uScanCode,
  _In_opt_  const BYTE *lpKeyState,
  _Out_     LPWORD lpChar,
  _In_      UINT uFlags
);

Parameters

uVirtKey [in]

Type: UINT

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

uScanCode [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 (not pressed).

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 (pressed).

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.

lpChar [out]

Type: LPWORD

The buffer that receives the translated character or characters.

uFlags [in]

Type: UINT

This parameter must be 1 if a menu is active, or 0 otherwise.

Return value

Type: int

If the specified key is a dead key, the return value is negative. Otherwise, it is one of the following values.

Return valueDescription
0

The specified virtual key has no translation for the current state of the keyboard.

1

One character was copied to the buffer.

2

Two characters were copied to the buffer. This usually happens when a dead-key character (accent or diacritic) stored in the keyboard layout cannot be composed with the specified virtual key to form a single character.

 

Remarks

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

Typically, ToAscii performs the translation based on the virtual-key code. In some cases, however, bit 15 of the uScanCode parameter may be used to distinguish between a key press and a key release. The scan code is used for translating ALT+ number key combinations.

Although NUM LOCK is a toggle key that affects keyboard behavior, ToAscii ignores the toggle setting (the low bit) of lpKeyState (VK_NUMLOCK) because the uVirtKey parameter alone is sufficient to distinguish the cursor movement keys (VK_HOME, VK_INSERT, and so on) from the numeric keys (VK_DECIMAL, VK_NUMPAD0 - VK_NUMPAD9).

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
OemKeyScan
ToAsciiEx
ToUnicode
VkKeyScan
Conceptual
Keyboard Input

 

 

Community Additions

ADD
Show:
© 2014 Microsoft