[fpc-pascal]a problem about pascal programing

[Gabor DEAK JAHN]

At 12/15/2001 10:55 PM, you wrote:

Wen-jei,

 > I am beginner of pascal programing. I have a question about that I can't 
use
 > a numeral as am element of enumerated data type such as "type
 > items=(1,2,3,4)". You may refer to the attached file to get more 
information

You're mixing two different concepts. Enumeration is a series of constants,
practically a simpler way to specify a series of constants. This means that
the elements of the list have to be identifiers, not numbers like in your
"type items = (1,2,3,4)" line.

What you are looking for is a subrange type, an integer whose range of
possible values is reduced. You can declare it with the syntax "type items =
1..4".

It depends on your actual requirements whether you need this or not. In your
program, you don't. If you step a variable from 4 to 1 with the compiler,
you can be sure the value will iterate from 4 to 1 all right, there is no
need for additional checking. But even if you need some range checking in
other places, you probably don't want to have a hostile runtime error, so
using a simple IF and showing your own error message (or correcting the
error yourself is it is feasible in the actual situation) could be a much
better alternative.


Bye,
    Gábor

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Gabor DEAK JAHN -- Budapest, Hungary.
E-mail: djg at tramontana.co.hu