TI-BASIC Tutorial - Loops

**exfyre** · 08-28-2009, 07:18 PM

Introduction
TI-BASIC is the built-in program language that comes with the TI-83/84+ calculators
Optional Resources
1. TI-83 Plus Flash Debugger -> for running programs
2. TI Graph link -> For writing & saving programs
-or-
a TI-83/84 Plus calculator -> writes and runs programs

Loops
Loops are groups of code that run until a condition is met.
Ti-BASIC loops can be created 3 different ways:
First, there are While and Repeat loops
Secondly, there are For( loops
and Lastly, Lbl loops.

While:
If the condition is met, it runs the code between the While and the End until the condition is false.
For example:

Code:

:0→X
:While X<5
:X+1→X
:Output(1,X,"V"
:End

Outputs:
VVVVV

Repeat:
If the condition is NOT met, it runs the code between the While and the End until the condition is TRUE.
For example:

Code:

:0→X
:Repeat X<5
:X+1→X
:Output(1,X,"V"
:End

Outputs:

You can think of Repeat as Repeat Until <condition>

For(:
For( is one of the more useful loop variations.
Syntax For(<var>, START, END, INC
So to generate the same output as the While loop above,

Code:

:For(X,1,5,1
:Output(1,X,"V"
:End

Outputs:
VVVVV

As you can see, using For( can really save some space and makes code look nicer.
NOTE: If you leave off the last argument, the INC defaults to 1. The code will also run faster with the last argument omitted

Lbl:
Most beginners at TI-BASIC tend to use Lbl loops because they make more sense to them. Experienced user do not. One reason is that when going to a label from inside a <insert command here> ... End statement, a memory leak occurs, which reduces the available memory by around 7 bytes (which is a lot in TI-BASIC!) Another reason Lbls are avoided is because they are slow.

To create a label loop:

Code:

:0→X
:Lbl ST
:X+1→X
:Output(1,X,"V"
:If X=5
:Goto ED
:Goto ST
:Lbl ED

Outputs:
VVVVV

Challenge Question Answer:

Code:

prgmGUESSING
:25→X
:While X≠A
:Input A, "Guess Number: "
:If A=X
:Then
:Disp "That's Right!"
:Else
:If A>X
:Disp "Too High!"
:If A<X
:Disp "Too Low!"
:End
:End