Texas Instruments TI-89 Manual Book page 315

Tip: You can declare the
counter variable as local
(pages 288 and 290) if it
does not need to be saved
after the program stops.
While...EndWhile
Loops
Note: The While command
does not automatically
change the condition. You
must include commands
that allow the program to
exit the loop.
298 Chapter 17: Programming
For example:
Displays 0, 1, 2, 3, 4, and 5.
Displays 6. When variable
increments to 6, the loop
is not executed.
A loop repeats a block of commands as long as a
While...EndWhile
specified condition is true. The syntax of the
While condition
When While is executed, the condition is evaluated. If condition is
true, the loop is executed; otherwise, program control jumps to the
command following
EndWhile
x ‚ 5
x < 5
At the end of the loop (
EndWhile
the command, where condition is re-evaluated.
While
To execute the loop the first time, the condition must initially be
true.
¦
Any variables referenced in the condition must be set before the
command. (You can build the values into the program or
While
prompt the user to enter the values.)
¦
The loop must contain commands that change the values in the
condition, eventually causing it to be false. Otherwise, the
condition is always true and the program cannot exit the loop
(called an infinite loop).
For example:
Initially sets x.
Displays 0, 1, 2, 3, and 4.
Increments x.
Displays 5. When x
increments to 5, the loop is
not executed.
:For i,0,5,1
: Disp i
:EndFor
:Disp i
While
.
:While x<5
: --------
: --------
:EndWhile
:--------
), program control jumps back to
:0! x
:While x<5
: Disp x
: x+1! x
:EndWhile
:Disp x
command is: