Programing advice please (50g)

[FLISZT]

(06-30-2023 04:39 PM)mchris Wrote:  Thank you all, it worked but I struggle to understand it

The regular syntax - as mentioned by Nigel (UK) - is:

Code:

<< TEST << … … >> IFT >>
            ↑
    if the test is true

or

Code:

<< TEST << … >> << … >> IFTE >>
           ↑       ↑
the test is true   the test is false

But instead of instructions inside chevrons, you can use lists (at least with hp-48GX … 50G / not with hp-28):

Code:

<< TEST { … … } { … … } IFTE >>

… generally, this syntax is faster than the one with chevrons (and lighter if my memory serves me right).

It's also possible to use a TAG :: before ONE instruction.
For example:
<< DUP2 > :: SWAP :: DROP2 IFTE >>

Last but not least example:
<< 1 == << 9 'l' STO+ >> IFT >>
… add 9 to the register l, if the value on the stack is equal to 1.

But… writing 'l' is impossible inside a list.
So, if you want use lists, the only solution I know of is that one (with a TAG):
<< 1 == { 0 ::l STO+ } IFT >>

I hope I'm clear enough…
Anyway, DavidM's solution to your question is the best.

Edit: typo