Re: [bug-gawk] [BUG] Diffent outputs from gawk and mawk

[Assaf Gordon]

Hello Jozef,

On 04/27/2015 02:23 PM, Jozef Zuzelka wrote:
<...>
> awk 'length > 127 {print substr ($0, 0, 127)"\t"$2} length < 128 {print 
> $1"\t"$2}'
<...>
> I think that /mawk/ is the one with correct output, but I may be wrong. I 
> attached you printscreen witch outputs.

I think the issue might be in your 'substr()' usage.
awk strings and arrays are 1-based, so the first position should be 
'substr($0,1,127)'.

Using 1 as the first position - gawk and mawk return the same value:

    $ echo "123456789" | gawk '{print substr($0,1,5)}'
    12345
    $ echo "123456789" | mawk '{print substr($0,1,5)}'
    12345

Using 0 as the first position (which I believe is invalid usage), mawk returns 
a string shorter by one character:

    $ echo "123456789" | gawk '{print substr($0,0,5)}'
    12345
    $ echo "123456789" | mawk '{print substr($0,0,5)}'
    1234

Changing 0 to 1 in the your substr example, both return 129 which is correct:
127 character from the substr + 1 tab + 1 newline.

HTH,
 -assaf