INKEY()

Topic group Related topics Example

Gets the first keystroke waiting in the keyboard typeahead buffer. Can also be used to wait for a keystroke and return its value.

Syntax

INKEY([<seconds expN>] [, <mouse expC>])

The number of seconds INKEY( ) waits for a keystroke. Fractional times are allowed. If <expN> is zero, INKEY( ) waits indefinitely for a keystroke. If <expN> is less than zero, the parameter is ignored.

Determines whether INKEY( ) returns a value when you click the mouse. If <expC> is "M" or "m", INKEY( ) returns –100. If <expC> is not "M" or "m", INKEY( ) ignores a mouse click and waits for a keystroke.

Description

The keyboard typeahead buffer stores keystrokes the user enters while dBASE Plus is busy. A very fast typist may also fill the keyboard typeahead buffer—dBASE Plus is busy trying to keep up. These keystrokes are normally handled automatically; for example, characters are typed into entryfields and menu choices are made. Use INKEY( ) to handle the keystrokes yourself.

INKEY( ) returns the decimal value associated with the first key or key combination held in the keyboard typeahead buffer and removes that keystroke from the buffer. If the typeahead buffer is empty, INKEY( ) returns the value of zero.

Key pressed	Return value	Shift+key return value	Ctrl+Key return value	Alt+key* return value
0	48	Depends on keyboard	–404	–452
1	49	Depends on keyboard	–404	–451
2	50	Depends on keyboard	–404	–450
3	51	Depends on keyboard	–404	–449
4	52	Depends on keyboard	–404	–448
5	53	Depends on keyboard	0	–447
6	54	Depends on keyboard	–30	–446
7	55	Depends on keyboard	–404	–445
8	56	Depends on keyboard	–404	–444
9	57	Depends on keyboard	–404	–443
a	97	65	1	–435
b	98	66	2	–434
c	99	67	3	–433
d	100	68	4	–432
e	101	69	5	–431
f	102	70	6	–430
g	103	71	7	–429
h	104	72	8	–428
i	105	73	9	–427
j	106	74	10	–426
k	107	75	11	–425
l	108	76	12	–424
m	109	77	13	–423
n	110	78	14	–422
o	111	79	15	–421
p	112	80	16	–420
q	113	81	17	–419
r	114	82	18	–418
s	115	83	19	–417
t	116	84	20	–416
u	117	85	21	–415
v	118	86	22	–414
w	119	87	23	–413
x	120	88	24	–412
y	121	89	25	–411
z	122	90	26	–410
F1 (Ctrl+\)	28	–20	–10	–30
F2	–1	–21	–11	–31
F3	–2	–22	–12	–32
F4	–3	–23	–13	–33
F5	–4	–24	–14	–34
F6	–5	–25	–15	–35
F7	–6	–26	–16	–36
F8	–7	–27	–17	–37
F9	–8	–28	–18	–38
F10	–9	–29	–19	–39
F11	–544	–546	–548	–550
F12	–545	–547	–549	–551
Left Arrow	19	–500	1	0
Right Arrow	4	–501	6	0
Up Arrow	5	5	5	0
Down Arrow	24	24	24	0
Home (Ctrl+])	26	26	29	0
End	2	2	23	0
Tab	9	–400	0	0
Enter	13	0	–402	0
Esc (Ctrl+[)	27	27	-	-
Ins	22	0	0	0
Del	7	–502	7	7
Backspace	127	127	–401	–403
PgUp	18	18	31	0
PgDn	3	3	30	0

Note

The Alt+key value returned for all character keys, except lower-case letters a through z, is the character value minus 500. For lower-case letters, the Alt+key values are the same as those for upper-case letters.

Because of the event-driven nature of dBASE Plus, INKEY( ) is rarely used. When it is used, it’s in one of three ways:

When keystrokes are expected to be buffered, INKEY( ) is used to get those keystrokes.

In a loop that’s busy doing something, INKEY( ) is used to see if a key has been pressed, and if so to take an action.

INKEY( ) can be used to wait for a keystroke, and then take an action.

In any of these cases, because dBASE Plus is busy executing your INKEY( ) code, it will not respond to keystrokes and mouse clicks as it normally would.

To check if there is a key waiting in the buffer without removing it, or to determine a value in the buffer in a position other than the first position, use NEXTKEY( ).