Yes there is - try looking under STATUS VARIABLES, they are intended for this kind of thing and there is a good example if I remember correctly.

So I don't see where there is a problem on that one!

To reduce the amount of 'gold' your player has when he buys something, you set the status variable exactly as if it were a regular numeric one. e.g.

set <money;%money%-20>

would reduce the amount of money by 20.

quote:

---

' "Buying Demo"
' Created with QDK Pro 3.12

define game <Buying Demo>
asl-version <311>
start <Shop>
game author <MaDbRiT>
game version <1.0>
game copyright <� 2003 MaDbRiT>
game info <Buying things demo>
define variable <money>
type numeric
value <100>
display <$$! dollar*s*>
onchange if ( %money% <= 0 ) then playerlose
end define
end define

define synonyms
end define

define room <Shop>
prefix <The Hardware>
look <a small hardware shop.>
command <buy widget> {
set <money;%money%-50>
move <widget;inventory>
msg <You hand over a fifty, and take the widget.>
}

define object <widget>
look msg <it's a blue widget, priced at 50 dollars.>
prefix <a>
end define

end define

define text <intro>

end define

define text <win>

end define

define text <lose>

end define

---

Hope that helps.

IF player has object "sword"
OR string 1 "money" is less than or equal too "0"

THEN msg "you cannot buy this"

You are making this MUCH too difficult!

All you need is ONE 'buy' command, and to give every object you want it possible to buy at any time a 'price' property.

Then in your buy command you...

a: check the object has a price property (if it doesn't it isn't buy-able).
b: check it is available to the player
c: check the player doesn't already have it
d: check the player has enough money.

If all the conditions are O.K. then you give the player the object and remove the value of its 'price' property from the player's money. If it fails at any stage you print an appropriate message to the player telling him why. This way coding one buy command will deal with all objects that have a price - makes sense - yes?

By the same method, you can code one SELL command to deal with all the possible sell-able items, testing the price property again as a key and of course ensuring the player actually HAS the item he's trying to sell.

I was well aware that the demo didn't prevent the player buying more than he has money to afford, I wasn't trying to offer you a complete solution, only to point you in the right direction so that you could solve it yourself! :-)

Al