HP 49g Graphing Calculator - Manual (Page 202)

Example
The following example creates the list of marks used in the previous
example. If a non-numeric value is entered, the program prompts with an
error message. The program performs the following:
® It sets up a loop to collect 20 values.
® It prompts for an input value.
® It tests the input to check if it is a number.
® If the generates an error, the error is trapped, and an error message is
displayed to prompt for a numeric value.
«
@ S e t n u m e r i c m o d e s o t h a t e r r o r t r a p w o r k s
S F { - 3 ) ;
@ C r e a t e a n e m p t y l i s t
{}► marks ;
@ S e t u p a l o o p f o r 2 0 e n t r i e s .
W H I L E S I Z E ( M A R K S ) < 2 0 R E P E A T
@ S t a r t e r r o r - c h e c k i n g r o u t i n e .
I F E R R I N P U T ( " E n t e r a n u m b e r " , " " ) N
@ A t t e m p t t o c o n v e r t t h e e n t r y t o a n u m b e r .
@ T h i s g e n e r a t e s a n e r r o r i f n o n - n u m e r i c
« O B J ^ ( N ) + l - l - y N
® I f n o e r r o r , a p p e n d t h e e n t r y t o t h e l i s t .
« MARKS+N ► MARKS
THEN
©This appears if entry is non-numeric.
MSGBOX("INVALID ENTRY, TRY AGAIN")
END ;
END
Page 10-16 Introduction to programming