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apalert
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Joined: 06/07/2023
Location: Australia
Posts: 47

Posted: 01:06pm 11 Jun 2026

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Looking to wait for Up or Down arrow to be pressed. Just to test the idea I've been inputting this and similar at the command prompt but doesn't work as hoped!

x=1 : do : loop while inkey$="" : if inkey$ = chr$(128) then x = x+1 : Print x

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 11479

Posted: 01:17pm 11 Jun 2026

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inkey$ consumes the keypress so you can't read it again

Do
x=1
s$=Inkey$
Loop While s$=""
If s$=Chr$(128) Then x=x+1:Print x

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 3285

Posted: 01:22pm 11 Jun 2026

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To make it work on one line:-

> x=1 : do : loop until inkey$ = chr$(128) : inc x : Print x
2
>

apalert
Regular Member

Joined: 06/07/2023
Location: Australia
Posts: 47

Posted: 08:52pm 11 Jun 2026

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Thanks Peter as always!

Thanks Phil, you've woken me up to using the INC function as well! I figured you can get a decrement using INC variable, -1. Oh boy, when I think of the copious variable = variable + 1 and variable = variable - 1 in my code. Not only does INC look slick, the manual says it processes much faster.

I actually want bigger steps than 1 so I've ended up, as a demo for using both Up and Down keys, with:

dim float x
dim string s$

x=10
do
Do
s$=Inkey$
Loop While s$=""
If s$=Chr$(128) Then inc x,10:Print x
If s$=Chr$(129) Then inc x,-10:Print x
loop

PhenixRising
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Joined: 07/11/2023
Location: United Kingdom
Posts: 1944

Posted: 07:59am 15 Jun 2026

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apalert said Not only does INC look slick, the manual says it processes much faster.

Please verify this. It definitely was true but when I tested with Tracecache, the old method was faster.

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 3285

Posted: 08:39am 15 Jun 2026

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> Clear :dim integer n, m
> t=timer:for m=0 to 999999: inc n :next:? timer-t,n,m
3148.165 1000000 1000000
> Clear :dim integer n, m
> t=timer:for m=0 to 999999: n=n+1 :next:? timer-t,n,m
5609.588 1000000 1000000
> option list
PicoMiteVGA MMBasic RP2350A Edition V6.03.00RC15
OPTION RESOLUTION 800x600 @ 360000KHz

For comparison the same loop doing nothing.

> Clear :dim integer n, m
> t=timer:for m=0 to 999999: :next:? timer-t,n,m
1227.124 0 1000000
>

Edited 2026-06-15 18:50 by phil99

toml_12953
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Joined: 13/02/2015
Location: United States
Posts: 652

Posted: 11:03am 15 Jun 2026

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PhenixRising said

apalert said Not only does INC look slick, the manual says it processes much faster.

Please verify this. It definitely was true but when I tested with Tracecache, the old method was faster.

In the following program, replacing statements in the DO LOOP with INC
shaved a few tenths of a second off the time thereby raising the Index:

TIMER =0
CONST loops%=9865
DIM float x, r0
DIM integer i
FOR i=1 TO loops
r0=10
DO
x=r0
INC x
INC x,-4.567e-4
INC x,70
INC x,-69
x=x*7
x=x/11
INC r0,-1
LOOP WHILE r0>0
x=LOG(x)
x=SIN(x)
x=SQR(x)
x=SQR(x)
NEXT i
PRINT x
t=TIMER/1000
PRINT "Loops:";loops
PRINT "Time:";t;" seconds"
PRINT "Index:";34/t*loops

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