TIB: Lists
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TIB: Lists
SWISH 97 wrote:
>
> Hey, i was told that i need to make a list to have the items thing in
my game
> were people can buy items and if they have it it shows up on the screen
but if
> they dont it doesn't, can someone explain to me(us all) how to make a
> list?-thanx-Frank
Another method exists which can be quite confusing, but saves lots of
RAM. The name of the technique is "bitwise manipulation," and is useful
if you are recording only the _presence_ or _absence_ of an item.
Examine the following code segments (keep in mind, comments cannot be
included in TI-BASIC).
:0 -> INV (* Sets up inventory variable. Notice it is of type REAL,
taking up ~20 bytes *)
:Input "Which item do you want to add: ",N
:INV or 2^(N-1) -> INV
:Input "Which item do you want to check: ",N
:If INV and 2^(N-1)
:Then
(* Statements-if-player-has-item *)
:Else
(* Statements-if-player-lacks-item *)
:End
:Input "Which item do you want to remove: ",N
:If INV and 2^(N-1):INV-2^(N-1) -> INV
Input "Which item do you want to change: ",N
:INV xor 2^(N-1) -> INV
Hope this helps!
Kevin J. DeGraaf
Class of 1999, Unity Christian High School
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