HP Prime: BREAK vs. CONTINUE
Introduction
Ever needed to end a loop early? Find yourself executing a loop where the
counter becomes a value that causes an execution error? An example where this might happen is a loop
where a function is divided by the counter variable, and during the loop the
counter variable takes the value of 0.
The HP Prime offers two ways to mitigate potential problems
in loops:
1. You can terminate
the loop at that point by using BREAK.
2. You can skip that
loop’s iteration by using CONTINUE.
You can specify how many loop structures are affected by
using either the BREAK n or CONTINUE n format.
A Simple Example
The programs LOOPED1 and LOOPED2 has a FOR structure that
divides 10 by every integer from -5 to 5.
(10/-5, 10/-4, etc..)
We can see that the counter will have a problem when the
variable reaches 0. Division by 0 will
cause an error and stop execution. We
are going to use BREAK and CONTINUE to mitigate this problem.
LOOPED1 – Break
EXPORT LOOPED1()
BEGIN
// Demonstration: BREAK
LOCAL x,y;
y:={};
// Loop
FOR x FROM −5 TO 5 DO
// Since we can′t
// divide by 0...
IF x==0 THEN
BREAK;
END;
y:=CONCAT(y,{10/x});
END;
RETURN y;
END;
When x=0, the for-loop is
stopped. As a result LOOPED1 returns:
{-2, -2.5, -3.333333333, -5, -10}
LOOPED2 – CONTINUE
EXPORT LOOPED2()
BEGIN
// Demonstration: CONTINUE
LOCAL x,y;
y:={};
// Loop
FOR x FROM −5 TO 5 DO
// Since we can′t
// divide by 0...
IF x==0 THEN
CONTINUE;
END;
y:=CONCAT(y,{10/x});
END;
RETURN y;
END;
In this case when the for-loop
encounters x=0, that iteration is skipped and the loop continues.
Result: {-2, -2.5, -3.333333333, -5, -10, 10, 5,
3.333333333, 2.5, 2}
Eddie
This blog is property of Edward
Shore, 2017.
