WM_CHAR
tchCharCode = (TCHAR) wParam; /* character code */
lKeyData = lParam; /* key data */
The WM_CHAR message is posted to the window with the keyboard focus when a WM_KEYDOWN message is translated by the TranslateMessage function. It contains the character code of the key that was pressed.
The WM_CHAR message may be used as either a wide-character message (where text arguments must use Unicode) or an ANSI message (where text arguments must use characters from the Windows 3.x character set).
tchCharCode
Value of wParam. Specifies the character code of the key.
lKeyData
Value of 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:
| Value | Description |
| 0–15 | Specifies the repeat count. The value is the number of times the keystroke is repeated as a result of the user holding down the key. |
| 16–23 | Specifies the scan code. The value depends on the original equipment manufacturer (OEM). |
| 24 | Specifies whether the key is an extended key, such as a function key or a key on the numeric key pad. The value is 1 if it is an extended key; otherwise, it is 0. |
| 25–28 | Reserved. |
| 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. |
An application should return zero if it processes this message.
Since 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 lKeyData 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 IBM Enhanced 101- and 102-key keyboards, extended keys are the right ALT and the right CONTROL keys on the main section of the keyboard; the INSERT, DELETE, HOME, END, PAGE UP, PAGE DOWN and DIRECTION keys in the clusters to the left of the numeric key pad; and the divide (/) and ENTER keys in the numeric key pad. Some other keyboards may support the extended-key bit in the lKeyData parameter.
TranslateMessage, WM_KEYDOWN