Lazarus
Home
Help
TinyPortal
Search
Login
Register
Lazarus
»
Forum
»
Free Pascal
»
Beginners
(Moderators:
FPK
,
Tomas Hajny
) »
Why is an enumeration out of range error not cought compile time
Free Pascal
Website
Downloads
Wiki
Documentation
Bugtracker
Mailing List
Lazarus
Website
Downloads (Laz+FPC)
Packages (OPM)
FAQ
Wiki
Documentation (RTL/FCL/LCL)
Bugtracker
CCR Bugs
IRC channel
GIT
Mailing List
Other languages
Foundation
Website
Useful Wiki Links
Project Roadmap
Getting the Source
Screenshots
How to use the forum
About donations (wiki)
Bookstore
Computer Math and Games in Pascal
(preview)
Lazarus Handbook
Search
Advanced search
Recent
DbGrid, grid column check...
by
KodeZwerg
[
Today
at 12:08:29 am]
Colore celle StringGrid
by
JuanBell
[April 24, 2024, 10:37:56 pm]
FpDebug likely bug
by
440bx
[April 24, 2024, 10:12:59 pm]
Any upgrades to fpWeb pag...
by
verasan
[April 24, 2024, 10:11:46 pm]
Web Applications with Pas...
by
Handoko
[April 24, 2024, 08:56:29 pm]
AI, NLP and CAI: Text Gen...
by
indydev
[April 24, 2024, 08:54:00 pm]
Offical launch of the 1 B...
by
Gustavo 'Gus' Carreno
[April 24, 2024, 08:48:22 pm]
Multidimensional arrays a...
by
KodeZwerg
[April 24, 2024, 08:34:38 pm]
Ho Ho Ho IntraWeb in Laza...
by
Thaddy
[April 24, 2024, 08:31:29 pm]
[SOLVED] System.Now gives...
by
alpine
[April 24, 2024, 08:29:19 pm]
open dialog - default dir...
by
Nicole
[April 24, 2024, 08:02:40 pm]
Installing and using Vamp...
by
Odacir
[April 24, 2024, 07:58:22 pm]
Demo Scene Picture sinwav...
by
circular
[April 24, 2024, 07:27:02 pm]
Demo Scene Bitmap Font Sc...
by
KodeZwerg
[April 24, 2024, 07:21:14 pm]
what's difference between...
by
ASerge
[April 24, 2024, 07:09:52 pm]
splitting an image
by
KodeZwerg
[April 24, 2024, 07:07:21 pm]
Debugger error
by
bobonwhidbey
[April 24, 2024, 07:03:07 pm]
How to: create DLL file f...
by
paule32
[April 24, 2024, 07:02:31 pm]
Your best UI design - con...
by
circular
[April 24, 2024, 06:48:12 pm]
Converting a string/index...
by
1HuntnMan
[April 24, 2024, 06:35:19 pm]
Drawing grid lines on a t...
by
KodeZwerg
[April 24, 2024, 05:42:19 pm]
Compile/Convert Delphi pr...
by
Martin_fr
[April 24, 2024, 05:29:03 pm]
Lazarus features in a non...
by
Lutz Mändle
[April 24, 2024, 05:26:34 pm]
Lazarus for Windows on aa...
by
msintle
[April 24, 2024, 05:03:57 pm]
Parameter passing odditie...
by
KodeZwerg
[April 24, 2024, 03:41:49 pm]
« previous
next »
Print
Pages: [
1
]
Author
Topic: Why is an enumeration out of range error not cought compile time (Read 983 times)
Anonimista
New Member
Posts: 19
Why is an enumeration out of range error not cought compile time
«
on:
September 11, 2019, 08:53:44 pm »
I have this code:
Code: Pascal
[Select]
[+]
[-]
program
project1
;
type
shape
=
(
rectangle
,
square
,
ellipse
,
circle
)
;
color
=
(
red
,
yellow
,
green
)
;
sex
=
(
male
,
female
)
;
var
s
:
sex
;
c
:
color
;
begin
s
:
=
male
;
writeln
(
s
)
;
writeln
(
succ
(
s
)
)
;
{ writeln(pred(s)); -- Runtime error 107 }
writeln
(
ord
(
pred
(
s
)
)
)
;
c
:
=
red
;
writeln
(
c
)
;
writeln
(
succ
(
c
)
)
;
readln
;
end
.
The error is "Invalid enumeration
Reported when a text representation of an enumerated constant cannot be created in a call to str or write(ln)."
Can anybody explain why this error is not caught at compile time. Is it to keep the compiler simple?
Logged
jamie
Hero Member
Posts: 6131
Re: Why is an enumeration out of range error not cought compile time
«
Reply #1 on:
September 11, 2019, 09:15:11 pm »
Delphi help says not to use a PRED on a WRITE operation because WRITE does not have a way to translate it to something usable.
In your example, you are actually faulting it because you are going outside the boundaries.
«
Last Edit: September 11, 2019, 09:18:00 pm by jamie
»
Logged
The only true wisdom is knowing you know nothing
Anonimista
New Member
Posts: 19
Re: Why is an enumeration out of range error not cought compile time
«
Reply #2 on:
September 11, 2019, 09:22:07 pm »
hm, I only get the error when ord(s) is -1. I guess my question is why are enumeration bounds not checked at compile time.
Logged
marcov
Administrator
Hero Member
Posts: 11459
FPC developer.
Re: Why is an enumeration out of range error not cought compile time
«
Reply #3 on:
September 11, 2019, 09:22:52 pm »
I think pred(s) and succ(s) are simply not inlined as intrinsics in this code. Then the increment/decrement doesn't happen in compiletime, so no error.
Logged
Anonimista
New Member
Posts: 19
Re: Why is an enumeration out of range error not cought compile time
«
Reply #4 on:
September 11, 2019, 09:43:29 pm »
Thanks! New to freepascal and not quite understand much but it is what it is.
Logged
Print
Pages: [
1
]
« previous
next »
Lazarus
»
Forum
»
Free Pascal
»
Beginners
(Moderators:
FPK
,
Tomas Hajny
) »
Why is an enumeration out of range error not cought compile time
TinyPortal
© 2005-2018