ToAsciiEx 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 input locale identifier.

Syntax

int ToAsciiEx(
  UINT       uVirtKey,
  UINT       uScanCode,
  const BYTE *lpKeyState,
  LPWORD     lpChar,
  UINT       uFlags,
  HKL        dwhkl
);

Parameters

uVirtKey

Type: UINT

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

uScanCode

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

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 SCOLL LOCK keys is ignored.

lpChar

Type: LPWORD

A pointer to the buffer that receives the translated character or characters.

uFlags

Type: UINT

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

dwhkl

Type: HKL

Input locale identifier to use to translate the code. This parameter can be any input locale identifier previously returned by the LoadKeyboardLayout function.

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 value Description
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 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 ToAsciiEx function might not be sufficient to translate the virtual-key code, because a previous dead key is stored in the keyboard layout.

Typically, ToAsciiEx 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, ToAsciiEx 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]
Target Platform Windows
Header winuser.h (include Windows.h)
Library User32.lib
DLL User32.dll

See Also

Conceptual

Keyboard Input

LoadKeyboardLayout

MapVirtualKeyEx

Reference

ToUnicodeEx

VkKeyScan