[Graham]

I've been trying to figure out how to input a string and then print it to the vlayer for use in an options panel. I thought this might work:

% "~eChange controller type"

? "keyboard" "Keyboard"
? "xbox" "Xbox 360 controller"
? "custom" "Other game controller"
goto "waitforit"

: "custom"
input string "Name of controller"
set "$controller#20" to "input"
loop start
set "vch&('loopcount'+5)&,22" to "$controller.&loopcount&"
set "vco&('loopcount'+5)&,22" to 23
loop for 19
goto "waitforit"

I had hoped it would allow me to input a controller name then it would place that name in a section of the vlayer. But It doesn't work for a couple of reasons. First, I can't substitute the X coordinate in 'VCHx,y' with an expression. I can substitute it with a counter like loopcount inside of ampersands, &loopcount&. But when I try to make an expression, it comes out 0. Second, the second value (that VCHx,y is set to) has to be a number corresponding to the char set. counters evidently don't work here. It has to be '175' or something like that.

Am I making a rookie mistake? Am I missing something? Is there a way to print a player inputted string to the physical game board, overlay, or vlayer like i'm trying to do? Please help.

[Dr Lancer-X]

You want this:

set "vch('loopcount'+5),22" to "$controller.&loopcount&"
set "vco('loopcount'+5),22" to 23

Using ampersands AND parentheses results in two sets of interpolation, so it ends up working like this:

(let's say 'loopcount' is 0)

set "vch&('loopcount'+5)&,22" to "$controller.&loopcount&"

set "vch&(0+5)&,22" to "$controller.0"

set "vch&5&,22" to "$controller.0"

You can see the problem in the last line: it reads from the counter "5", which is probably 0 (because it's undefined)

[Wervyn]

This looks like a simple rookie mistake, you're mixing ampersand interpolation and expressions together in a way that's giving you unexpected results. Basically, when you're doing "vch&('loopcount'+5)&", you're doing two nested interpolations. The ampersands are unnecessary here, you can embed an expression into a counter name just fine using parentheses by themselves. What this does instead, is first resolve ('loopcount'+5), which comes out to some number (say 10), and then try to resolve &10&, looking for a counter literally named "10", which probably doesn't exist. So you get 0, because MZX error handling is all but non-existent. This is one of the most common bugs in MZX coding, and it can be devilish hard to catch: when your expression is malformed (mismatched parens, too much nesting), you just get bad counter reference that resolves to a silent 0.

As for the right-hand value, what you're doing there should work just fine. You're correct that as far as vchX,Y goes, you're setting a byte that references the character set. But that's also what you should be getting out of the string.

Of course, the easiest way to get your string in might be to just write the overlay directly: "write overlay c0f "&INPUT&" X Y". Then you can copy that to the vlayer if you want, and avoid processing the string by hand.

"Wait, I should be judging."

[Graham]

Ahh! Thanks guys! Big help. I should be able to get this program working like I wanted now. Thanks a lot.