The WM_CHAR message is posted to the window with the keyboard focus when a WM_KEYDOWN message is translated by the TranslateMessage function. The WM_CHAR message contains the character code of the key that was pressed.
Syntax
WM_CHAR WPARAM wParam LPARAM lParam;
Parameters
- wParam
- Specifies the character code of the key.
- lParam
- Specifies the repeat count, scan code, extended-key flag, context code, previous key-state flag, and transition-state flag, as shown in the following table.
0-15- Specifies the repeat count for the current message. The value is the number of times the keystroke is autorepeated as a result of the user holding down the key. If the keystroke is held long enough, multiple messages are sent. However, the repeat count is not cumulative.
16-23- Specifies the scan code. The value depends on the OEM.
24- Specifies whether the key is an extended key, such as the right-hand ALT and CTRL keys that appear on an enhanced 101- or 102-key keyboard. The value is 1 if it is an extended key; otherwise, it is 0.
25-28- Reserved; do not use.
29- Specifies the context code. The value is 1 if the ALT key is held down while the key is pressed; otherwise, the value is 0.
30- Specifies the previous key state. The value is 1 if the key is down before the message is sent, or it is 0 if the key is up.
31- Specifies the transition state. The value is 1 if the key is being released, or it is 0 if the key is being pressed.
Return Value
An application should return zero if it processes this message.
Remarks
The WM_CHAR message uses Unicode Transformation Format (UTF)-16.
Because there is not necessarily a one-to-one correspondence between keys pressed and character messages generated, the information in the high-order word of the lParam parameter is generally not useful to applications. The information in the high-order word applies only to the most recent WM_KEYDOWN message that precedes the posting of the WM_CHAR message.
For enhanced 101- and 102-key keyboards, extended keys are the right ALT and the right CTRL keys on the main section of the keyboard; the INS, DEL, HOME, END, PAGE UP, PAGE DOWN and arrow keys in the clusters to the left of the numeric keypad; and the divide (/) and ENTER keys in the numeric keypad. Some other keyboards may support the extended-key bit in the lParam parameter.
Windows XP: The WM_UNICHAR message is the same as WM_CHAR, except it uses UTF-32. It is designed to send or post Unicode characters to ANSI windows, and it can handle Unicode Supplementary Plane characters.
Notification Requirements
Minimum DLL Version None Header Declared in Winuser.h, include Windows.h Minimum operating systems Windows 95, Windows NT 3.1
See Also
Keyboard Input Overview, TranslateMessage, WM_KEYDOWN, WM_UNICHAR
