Goto And Labels

[EnderWiggin]

I was working on a prgm and i noticed that i couldn't use an equation in a goto. Is there a way to get around it?
This is an example of what i mean;

6->A
Repeat B=105
GetKey -> B
Text(1,A,"-"
If B=24 and A(not=s)6
Then
A-6->A
Text(1,A+6," "
End
If B=34 and A(not=s)48
Then
A+6->A
Text(1,A-6," "
End
End
Goto A/6
Lbl 1

Lbl 2

....


That's my program that doesn't work, if any one can tell me if it is possible to do some thing like this, it would be great!

[Toksyuryel]

1. You can't do that in BASIC.
2. Learn ASM.

[Jeremiah Walgren]

I believe it's the "/" in your label that's causing the problem.

[Arcane Wizard]

[Jeremiah Walgren]

Ahh, I see. Yeah, If - Then statements should work just fine.

[Arcane Wizard]

Actually, just if statements, if you use goto in a loop or open if..then..else..end statement, it will cause memory problems.

[Jeremiah Walgren]

I was just referring to them in general...

[EnderWiggin]

Thanks a lot!

If you were wondering, I was trying to make the program shorter by using an equation instead of If-Then statements, but I'l just use Arcane Wizard's method with "If Ans Goto 1..."

Thanks a lot guys

(I tried learning Asm but couldn't work it and gave up. I'll give it another try some day though)

[EnderWiggin]

Lets see....
hmmmmmmm will my picture work?
I hope so

[Jedd]

I've had the same problem with pictures. You can't use a variable or an equation to recall or store a pic. It's too bad because some games would run a lot faster.

[DarkerLine]

On the TI-89, you can use variables to recall pics, and I think (but am not sure) also Gotos. That is one of the reasons I am writing my rpg on the 89.

[Jedd]

Wow that would be so nice. Is the 89 a lot faster than the 83+? Is it faster than the SE? My friend with an 89 was asking me that today. I fooled around with it and its sooo confusing to me. 83 all the way.

[Jeremiah Walgren]

Yes, the 89 is faster than the 83+. (Even the SE if memory serves...) If you can figure out how to use the 89 then it's an awesome calculator to use.

[NETWizz]

Yeah, that is the problem.

Also, do not jump to a label from within a then statement, or from within any loop.

Jumps are okay, but do not use Goto to leave a loop. That is how unstable basic programs are made.

I don't have time to explain it all but:

lbl A
while 1
Goto A
End

run that, and the program will eventually display an error letting you know it ate all the system resources and crashed.

Just select Quit, and your calc will be perfectly fine.

[DarkerLine]

What does the error say? ERR:MEMORY?

[Jeremiah Walgren]

Yup.

I'm not sure on this, but I'll try to explain why. When the calculator encounters the "While" it looks for an "End" to complete the statement. Since there is a "Goto" inside the statement that takes program execution to the beginning of the loop it never finds the "End" it needs. Therefore, it basically keeps track, I guess you'd say, of how many Ends it needs to encounter. Eventually, it runs out of memory.

Like I said, I'm not sure if that's why so someone correct me if I'm wrong. (I could be totally off...)

[X1011]

[Jeremiah Walgren]

Point taken. However, compare the processor types as well.

[NETWizz]

Actually, you can even do this:

1->A
Goto B
Lbl A
Getkey
If Ans=32
0->A
End

Disp "ENDED AT 1
Stop

Lbl B
While A
Disp "HELLO
Goto A
End

Disp "ENDED AT 2

Here is how it works:

If A is 1, the While statement is an endless loop, but if A gets changed to 0, the loop stops evaluating as true; therefor the program ends!

So, we make A = 1, so the while statement is true, then we go to the endless loop.

It displays hello, then jumps out of the while loopand executes some more code. If clear is pressed, A is set to 0 ending the endless loop and the program.

Now, End is reached.

Well, the basic parser sees the end, and it thinks it belongs to the While loop, so it goes back there if A is 1 !

The same program could be written like this:

1->A
While A
getkey
If Ans=32
0->A
End


I do not know if it will end at 1 or 2, so run the program to find out!


You probalbly won't see much basic like that because it envolves the programmer haveing some idea of what goes on behind the seans.

Heck, we left a loop but continued because as far as the calc is concerned, you are in a loop until the End is met.

I just proved that the calc tracks loops until the end token is hit!