Sharp PC-1500A Instruction Manual page 38

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As an example of a program \Vhich fails to do this, enter the follo\ving:
Program Listing:
1
1
0 A = 0
20 INPUT A
30 PRINT A*PI
Keystrokes:
mmrn1
=
l (]]l••ru l
rn
oo rn
mm
OD
rn
m
1."' .. 1
rn oo moo
rn
oo
rn
m rn mm
,,.,,.1
Now imagine the user as he runs the program .. . The fi rst thing that appears on the display is
a question mark. 'The knowledgeable user will realize that some data is required but he will have no
idea what that data should be. Suppose he takes
a
wild guess,
and
luckily, enters a number.
Suddenly,
a
long and complicated number appears. What does it mean? He presses ENTER to
continue, but the program ends. From his viewpoint, the whole experience has been a waste of
time. Why? Because of poor programming .
One solution to this problem is to use PRINT o r PAUSE statements to help the user along.
With this idea we can re-write our program as follows:
Program Listing:
10 A = 0
20 PAUSE "ENTER ANY
NUMB ER"
30 INPUT A
40 AP = A*PI
50 PRINT A; " TIMES Pl
=
";AP
Keystrokes:
CD
rn rn
( ;; I
rn
l••u•I
m oo m rn m rn
IIl ' ""'''
1
c:i IIl
oo rn
IIl
m
'""•<•I
rnoom 1 .. •c•1rn oo@mmm ,..,,.,, c::i1 •• , •• ,
rn oo
rn rn m
o;o
co rn '""'""'
moomm1 =1rnrnmm1 ••TE•I
m rn mmrn oornrn ''"'"' 01 ... "'1 c:J l• ..
c•!
C!Jo::J
@CD
aJ
1 •,.e<I
ffi
o::J
1 s-.c<l I
=
I
l•••«I ''""' I
CJ
I'"'"
I
CJ
rn m
l•HT•• l
This version is much more useful because it "prompts" (or provokes) the user for input and
because it identifies the output.
36
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