Re: GAWK 3.1.1 bug, DJGPP port

[Serge Bohdjalian]

Hi Stephan,

Thanks for your response. In my ignorance, I didn't realize that "e" (or 
"E") could be used for base-10 exponent notation. This partly explained the 
strange behaviour I observed. (I would have thought that a "+" or "-" 
needed to follow the "e".)

At 2003.01.07 01:49 PM +0100, you wrote:
> Hello,
> Observe:
>         BEGIN {
>                 # first bug:
>                 $0 = "0 0e0"
>                 print $1 && 1, $2 && 2
>
>                 # second bug:
>                 $0 = "00"
>                 print $0 && 1
>
>                 # and even worse:
>                 $0 = a = "00"
>                 print a && 1
>         }
> gives
>         0 1
>         0
>         0
> while correct results are
>         0 0
>         1
>         1

Note that with 3 different versions of GAWK for Windows I get ...

C:\TEST>"C:\TEST\gawk310_SourceForge.exe" -f "TEST.AWK" "TEST.TXT"
0 1
1
1

C:\TEST>"C:\TEST\gawk311_Cygwin.exe" -f "TEST.AWK" "TEST.TXT"
0 1
0
0

C:\TEST>"C:\TEST\gawk311_DJGPP.exe" -f "TEST.AWK" "TEST.TXT"
0 0
0
0


(I assume my version of DJGPP GAWK doesn't have the patch you provided.)

I don't see why the last 2 expressions, as you state, should equal 1 
(TRUE). From what I understand, if "0" is compared to a numeric constant, 
"0" should be interpreted as a number. Presumably, the same principle 
should apply to "0e0". I don't understand why "0e0" is treated differently 
from "0". The GAWK documentation says...

...

In the next example:

$ echo 1e2 3 | awk '{ print ($1 < $2) ? "true" : "false" }'
-| false

...the result is "false" because both "$1" and "$2"
are user input. They are numeric strings -- therefore both have
the "strnum" attribute, dictating a numeric comparison.

...

When I run the following script...

BEGIN {
   $0 = "0";
   if ($0) print $0 " = TRUE"; else print $0 " = FALSE";

   $0 = "0e0";
   if ($0) print $0 " = TRUE"; else print $0 " = FALSE";
}

...I get the following output with my 3 versions of GAWK for Windows...

C:\TEST>"C:\TEST\gawk310_SourceForge.exe" -f "TEST.AWK" "TEST.TXT"
0 = FALSE
0e0 = TRUE

C:\TEST>"C:\TEST\gawk311_Cygwin.exe" -f "TEST.AWK" "TEST.TXT"
0 = FALSE
0e0 = TRUE

C:\TEST>"C:\TEST\gawk311_DJGPP.exe" -f "TEST.AWK" "TEST.TXT"
0 = FALSE
0e0 = FALSE

...

Before I knew that "0e0" could be interpreted as a number, I would have 
thought that the first 2 outputs (from SourceForge and Cygwin) were 
correct. Now I'm not so sure.

-Serge