Awk print statement alters the argument variable's content

Awk print statement alters the argument variable's content

[Lundberg Christer]

This program run with GNU awk 4.1.4 (currently installed with Cygwin):

  awk '
    BEGIN { OFMT="%.8g"
            buf = 1+0.1
            buf = buf "a"
            print "Length before print:", length(buf)
            print buf " "
            print buf
            print buf " "
            print "Length after print:", length(buf)
          }
  '

produces the following output on our system:

Length before print: 4
1.1a 
1.1
1.1 
Length after print: 3

so it appears that the "print buf" statement unexpectedly alters the content of buf.
With awk 4.1.3, we got the expected output

Length before print: 4
1.1a 
1.1a
1.1a 
Length after print: 4


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Re: Awk print statement alters the argument variable's content

[Brian Inglis]

On 2017-01-12 05:26, Lundberg Christer wrote:
> This program run with GNU awk 4.1.4 (currently installed with
> Cygwin):
> 
>   awk '
>     BEGIN { OFMT="%.8g"
>             buf = 1+0.1
>             buf = buf "a"
>             print "Length before print:", length(buf)
>             print buf " "
>             print buf
>             print buf " "
>             print "Length after print:", length(buf)
>           }
>   '
> 
> produces the following output on our system:
> 
> Length before print: 4
> 1.1a 
> 1.1
> 1.1 
> Length after print: 3
> 
> so it appears that the "print buf" statement unexpectedly alters the
> content of buf.
> With awk 4.1.3, we got the expected output
> 
> Length before print: 4
> 1.1a 
> 1.1a
> 1.1a 
> Length after print: 4

Confirmed problem with any OFMT except default or %.6g, also goes 
away if you change awk line 3 to: buf = "" buf "a":
 
$ uname -srvmo
CYGWIN_NT-10.0 2.6.1(0.305/5/3) 2016-12-16 11:55 x86_64 Cygwin
$ awk --version
GNU Awk 4.1.4, API: 1.1 (GNU MPFR 3.1.5, GNU MP 6.1.1)
Copyright (C) 1989, 1991-2016 Free Software Foundation.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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Re: Awk print statement alters the argument variable's content

[Corinna Vinschen]

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On Jan 13 01:31, Brian Inglis wrote:
> On 2017-01-12 05:26, Lundberg Christer wrote:
> > This program run with GNU awk 4.1.4 (currently installed with
> > Cygwin):
> > 
> >   awk '
> >     BEGIN { OFMT="%.8g"
> >             buf = 1+0.1
> >             buf = buf "a"
> >             print "Length before print:", length(buf)
> >             print buf " "
> >             print buf
> >             print buf " "
> >             print "Length after print:", length(buf)
> >           }
> >   '
> > 
> > produces the following output on our system:
> > 
> > Length before print: 4
> > 1.1a 
> > 1.1
> > 1.1 
> > Length after print: 3
> > 
> > so it appears that the "print buf" statement unexpectedly alters the
> > content of buf.
> > With awk 4.1.3, we got the expected output
> > 
> > Length before print: 4
> > 1.1a 
> > 1.1a
> > 1.1a 
> > Length after print: 4
> 
> Confirmed problem with any OFMT except default or %.6g, also goes 
> away if you change awk line 3 to: buf = "" buf "a":

It's an upstream bug.  I asked on the gawk ML.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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