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
FpDebug questions
by
440bx
[
Today
at 03:43:41 am]
Lazarus for Windows on aa...
by
Wallaby
[April 23, 2024, 11:46:56 pm]
Parameter passing odditie...
by
KodeZwerg
[April 23, 2024, 11:04:39 pm]
Can function be used for ...
by
jamie
[April 23, 2024, 10:53:10 pm]
(Solved) TIndexedAVLTree ...
by
lainz
[April 23, 2024, 10:49:03 pm]
Demo Scene Picture sinwav...
by
KodeZwerg
[April 23, 2024, 10:26:21 pm]
fkInternalCalc
by
zraja
[April 23, 2024, 09:31:07 pm]
A fairly simple sound sol...
by
KodeZwerg
[April 23, 2024, 09:23:37 pm]
add new targets to make
by
marcov
[April 23, 2024, 08:38:42 pm]
how to tweek fpmake to co...
by
marcov
[April 23, 2024, 08:29:16 pm]
Quirky windows
by
ASerge
[April 23, 2024, 07:07:16 pm]
[Request] Demo Scene Sub ...
by
Gigatron
[April 23, 2024, 06:29:39 pm]
Unlocking Files
by
KodeZwerg
[April 23, 2024, 06:03:08 pm]
[SOLVED] trunk bug for mi...
by
Key-Real
[April 23, 2024, 05:56:32 pm]
Demo Scene Bitmap Font Sc...
by
Gigatron
[April 23, 2024, 05:56:27 pm]
Compile/Convert Delphi pr...
by
Martin_fr
[April 23, 2024, 05:43:11 pm]
Generics - correct syntax
by
Thaddy
[April 23, 2024, 05:40:59 pm]
InstallAware Using Lazaru...
by
msintle
[April 23, 2024, 05:26:36 pm]
Xcode Command Line Tools ...
by
Joseph
[April 23, 2024, 05:16:39 pm]
Offical launch of the 1 B...
by
Hartmut
[April 23, 2024, 04:49:29 pm]
what to do if my target M...
by
nickysn
[April 23, 2024, 04:16:02 pm]
compiler error in unit
by
paule32
[April 23, 2024, 03:49:50 pm]
Multithreading - synchron...
by
mika
[April 23, 2024, 01:48:51 pm]
May be useful to somebody
by
KodeZwerg
[April 23, 2024, 12:38:22 pm]
match automatic highlight...
by
Чебурашка
[April 23, 2024, 11:35:14 am]
« previous
next »
Print
Pages: [
1
]
Author
Topic: Why is an enumeration out of range error not cought compile time (Read 981 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: 11458
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