trouble with {$IF ...}

David Emerson2-4-2004 09:58 UTC

I would like to do some very basic boolean operations within compiler directives. $IF does not seem to work reliably. See below:

C:\fpc\test>fpc directive_test -Sm
Free Pascal Compiler version 1.0.10 [2003/06/27] for i386 [...]
User defined: =========================
User defined: $define x:=17
User defined: !!! (x=5) = TRUE even though i set x:=17 User defined: . (x>50) = false (good, x=17)
User defined: !!! (x<50) = FALSE even though i set x:=17 User defined: !!! ($if 1 AND 0) = TRUE
User defined: =========================
User defined: $define zero:=0
User defined: !!! ($if zero) = TRUE
User defined: !!! ($if 0) = TRUE
User defined: and now the exact same test again... User defined: . ($if 0) = false
User defined: =========================
User defined: $define apples
User defined: !!! ($ifdef oranges or apples) = FALSE :-( User defined: =========================
Linking directive_test.exe
68 Lines compiled, 1.2 sec

I know boolean operators are not supported for $ifdef, but it would sure be nice.

The most baffling part is where {$IF 0} = true and then the same {$IF 0} = false. It seems to be related to the test done just prior to it -- If I follow the 'zero' test with the {$IF 0} test, the latter doesn't work.

Here is the source:

begin
{$info =========================}
{$define x:=17}
{$info $define x:=17}
{$if x=5}
   {$info !!! (x=5) = TRUE even though i set x:=17}
{$else}
   {$info .   (x=5) = false   (good, x=17)}
{$endif}
{$if x>50}
   {$info !!! (x>50) = TRUE even though i set x:=17}
{$else}
   {$info .   (x>50) = false   (good, x=17)}
{$endif}
{$if x<50}
   {$info .   (x<50) = true   (good, x=17)}
{$else}
   {$info !!! (x<50) = FALSE even though i set x:=17}
{$endif}
{$if 1 AND 0}
   {$info !!! ($if 1 AND 0) = TRUE}
{$else}
   {$info .   ($if 1 AND 0) = false}
{$endif}
{$info =========================}
{$define zero:=0}
{$info $define zero:=0}
{$if zero}
   {$info !!! ($if zero) = TRUE}
{$else}
   {$info .   zero returned false}
{$endif}
{$if 0}
   {$info !!! ($if 0) = TRUE}
{$else}
   {$info .   ($if 0) = false}
{$endif}
{$info and now the exact same test again...}
{$if 0}
   {$info !!! ($if 0) = TRUE}
{$else}
   {$info .   ($if 0) = false}
{$endif}
{$info =========================}
{$define apples}
{$info $define apples}
{$ifdef oranges or apples}
   {$info .   ($ifdef oranges or apples) = true}
{$else}
   {$info !!! ($ifdef oranges or apples) = FALSE   :-( }
{$endif}
{$info =========================}
end.

Peter Vreman2-4-2004 10:58 UTC

to David Emerson

Show quoted text 27 lines

I would like to do some very basic boolean operations within compiler directives. $IF does not seem to work reliably. See below: C:\fpc\test>fpc directive_test -Sm Free Pascal Compiler version 1.0.10 [2003/06/27] for i386 [...] User defined: ========================= User defined: $define x:=17 User defined: !!! (x=5) = TRUE even though i set x:=17 User defined: . (x>50) = false (good, x=17) User defined: !!! (x<50) = FALSE even though i set x:=17 User defined: !!! ($if 1 AND 0) = TRUE User defined: ========================= User defined: $define zero:=0 User defined: !!! ($if zero) = TRUE User defined: !!! ($if 0) = TRUE User defined: and now the exact same test again... User defined: . ($if 0) = false User defined: ========================= User defined: $define apples User defined: !!! ($ifdef oranges or apples) = FALSE :-( User defined: ========================= Linking directive_test.exe 68 Lines compiled, 1.2 sec I know boolean operators are not supported for $ifdef, but it would sure be nice.

This is even not supported in C. $ifdef is just a shortcut for $if defined(<name>). You must us '$if defined(oranges) or defined(apples)'.

The marcos work correct in the current development version 1.9.3:

Free Pascal Compiler version 1.9.3 [2004/02/04] for i386 Copyright (c) 1993-2004 by Florian Klaempfl
Target OS: Win32 for i386
Compiling p.pp
User defined: =========================
User defined: $define x:=17
User defined: . (x=5) = false (good, x=17)
User defined: . (x>50) = false (good, x=17)
User defined: . (x<50) = true (good, x=17)
User defined: . ($if 1 AND 0) = false
User defined: =========================
User defined: $define zero:=0
User defined: . zero returned false
User defined: . ($if 0) = false
User defined: and now the exact same test again... User defined: . ($if 0) = false
User defined: =========================
User defined: $define apples
User defined: !!! ($ifdef oranges or apples) = FALSE :-( User defined: =========================
Linking p.exe
69 Lines compiled, 0.2 sec

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trouble with {$IF ...}