A question about awk
Peter S Tillier
when I mentioned that I was a fan of awk, Eric asked me this question:
ep> Okay, here's a question I have for you that I'm
ep> tinkering with right now. What's the SHORTEST
ep> awk script to print a row of 65 hyphens?
ep>
ep> Here's what I've come up with, but I don't
ep> think it's the best:
ep>
ep> echo - | awk "{while(i<65){printf $1;i++}}"
ep>
ep> It's not exactly perl, which could say:
ep>
ep> perl -e "print \"-\" x 65;"
ep>
ep> but I'm interested in a GNU awk solution.
ep> Any ideas?
I came up with a few alternatives, but none actually significantly
shorter than Eric's above.
I can get a similar length program to perl in REXX;
rexx 'say substr("",1,65,"-")'
but I'd be interested to see if we can come up with a considerably
shorter version for gawk. A pity that gawk's substr doesn't work a bit
more like rexx's.
Thoughts anyone?
Regards,
Peter
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Peter S Tillier
"Who needs perl when you can write dc in sed?"
peter dot tillier at btinternet dot com
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Erik Christiansen
Peter S Tillier <pet...@deadspam.com> wrote:
>ep> Here's what I've come up with, but I don't
>ep> think it's the best:
>ep>
>ep> echo - | awk "{while(i<65){printf $1;i++}}"
Peter,
In real life we can call a function: repeat("-",65)
function repeat(x,n)
{ while (i < n)
printf("%s",x)
}
making each invocation suitably short.
But we can presumably also use gawk's new extension facility to incorporate
the function in the tool, if one of the rules in this game is to minimise
even a single invocation. :-)
Erik
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-- Grant Wood
Grod
> What's the SHORTEST awk script to print a row of 65 hyphens?
awk 'BEGIN{printf("%65s",x)}' | tr ' ' -
Jurgen Riepe
> ep>
> ep> echo - | awk "{while(i<65){printf $1;i++}}"
> ep>
Steps of the evolution:
echo - | awk "{while(i<65){printf $1;i++}}"
echo - | awk "{while(i++<65){printf $1}}"
awk 'BEGIN{printf "%065s",0}'| tr 0 -
pure awk, 14% less than the echo/awk version above, but still not very nice:
awk 'BEGIN{while(i++<65)printf "-"}'
Jurgen
Kenny McCormack
tawk 'BEGIN {print strdup("-",65)}'
gawk 'BEGIN {$0=sprintf("%65s",x);gsub(/ /,"-");print}'
Note that the later technique (using sprintf to build up the length -
padding with spaces - and then using gsub to change the spaces into the
char you want) is how I implement strdup in AWKs that don't have it.
Eiso AB
>
> A few weeks ago I was corresponding with Eric Pement about the sed FAQ,
> when I mentioned that I was a fan of awk, Eric asked me this question:
>
> ep> Okay, here's a question I have for you that I'm
> ep> tinkering with right now. What's the SHORTEST
> ep> awk script to print a row of 65 hyphens?
> ep>
> ep> Here's what I've come up with, but I don't
> ep> think it's the best:
> ep>
> ep> echo - | awk "{while(i<65){printf $1;i++}}"
> ep>
this one's a bit shorter
echo - | awk '{while(i++<64)$0=$0"-"}1'
though I don't like the "echo - |"
this one's even shorter, but cheats a bit
gawk --v | gawk '/n;/&&gsub(".","-")'
it might only work with gawk 3.1.0 ;-)
E
> ep> It's not exactly perl, which could say:
> ep>
> ep> perl -e "print \"-\" x 65;"
> ep>
> ep> but I'm interested in a GNU awk solution.
> ep> Any ideas?
>
> I came up with a few alternatives, but none actually significantly
> shorter than Eric's above.
>
> I can get a similar length program to perl in REXX;
>
> rexx 'say substr("",1,65,"-")'
>
> but I'd be interested to see if we can come up with a considerably
> shorter version for gawk. A pity that gawk's substr doesn't work a bit
> more like rexx's.
>
> Thoughts anyone?
>
> Regards,
> Peter
> --
> Peter S Tillier
> "Who needs perl when you can write dc in sed?"
> peter dot tillier at btinternet dot com
> To reply direct to me please use the above address
> not the "Reply To" which activates a spam trap.
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_________
_______________________________/ Eiso AB \_________________________
Bob Harris
S Tillier <peter....@btinternet.com> wrote:
X A few weeks ago I was corresponding with Eric Pement about the sed FAQ,
X when I mentioned that I was a fan of awk, Eric asked me this question:
X
X ep> Okay, here's a question I have for you that I'm
X ep> tinkering with right now. What's the SHORTEST
X ep> awk script to print a row of 65 hyphens?
X ep>
X ep> Here's what I've come up with, but I don't
X ep> think it's the best:
X ep>
X ep> echo - | awk "{while(i<65){printf $1;i++}}"
X ep>
X ep> It's not exactly perl, which could say:
X ep>
X ep> perl -e "print \"-\" x 65;"
X ep>
X ep> but I'm interested in a GNU awk solution.
X ep> Any ideas?
X
X I came up with a few alternatives, but none actually significantly
X shorter than Eric's above.
X
X I can get a similar length program to perl in REXX;
X
X rexx 'say substr("",1,65,"-")'
awk 'BEGIN{ s=sprintf("%65s",""); gsub(".","-",s); print s }'
Not as short all that short, but what the heck.
Bob Harris
Mark Katz
Jurge...@web.de "Jurgen Riepe" writes:
Pure awk, a bit longer and perhaps less 'not very nice' ;-))
awk 'BEGIN{x="-------------"; print x x x x x }'
Mark
---
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Tel: (44) 20-8731 7516, Fax: (44) 20-8458 9554; http://www.mark-it.co.uk
Brian Inglis
Katz) wrote:
>In article <b0a8f4e1.01083...@posting.google.com>
> Jurge...@web.de "Jurgen Riepe" writes:
>
>>"Peter S Tillier" <peter....@btinternet.com> wrote in message
>> news:<999209126.17243.0...@news.demon.co.uk>...
>>> ep> Here's what I've come up with, .........
>>> ep>
>>> ep> echo - | awk "{while(i<65){printf $1;i++}}"
>>> ep>
>>
>>Steps of the evolution:
>>
>>echo - | awk "{while(i<65){printf $1;i++}}"
>>echo - | awk "{while(i++<65){printf $1}}"
>>awk 'BEGIN{printf "%065s",0}'| tr 0 -
>>
>>pure awk, 14% less than the echo/awk version above, but still not very nice:
>>
>>awk 'BEGIN{while(i++<65)printf "-"}'
>
>Pure awk, a bit longer and perhaps less 'not very nice' ;-))
> awk 'BEGIN{x="-------------"; print x x x x x }'
>
The general approach to string repeats is, in awk:
function repeat(s,n)
{
n *= length( s ); # multiply n to length
while (length( s ) < n)
{
s = s s; # double length
}
s = substr( s, 1, n); # chop back as required
return s;
}
Thanks. Take care, Brian Inglis Calgary, Alberta, Canada
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Eiso AB
http://groups.google.com/groups?q=shortest+65-hyphens
The SHORTEST awk script to print a row of 65 hyphens ?
gawk 'BEGIN{$65=OFS="-";print}'
Eiso
Larry__Weiss
> This came up some time ago.
> http://groups.google.com/groups?q=shortest+65-hyphens
> The SHORTEST awk script to print a row of 65 hyphens ?
> gawk 'BEGIN{$65=OFS="-";print}'
>
Clever!
Here's a variation that gives a nice clean screen
afterwards in an MSDOS or Windows "DOS Prompt" environment:
gawk 'BEGIN{$9999=OFS=" ";print}'
GAWK allows this pattern to create files populated to exact sizes:
gawk 'BEGIN{$1000000=OFS=" ";printf("%s",$0)}' >xo
will result in file "xo" containing exactly 1 million space chars.
- Larry Weiss
John DuBois
Larry__Weiss <l...@airmail.net> wrote:
> gawk 'BEGIN{$1000000=OFS=" ";printf("%s",$0)}' >xo
>
>will result in file "xo" containing exactly 1 million space chars.
A slightly shorter version:
gawk 'BEGIN{printf("%1000000s","")}' >xo
John
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Peter S Tillier
<snip>
>
> Here's a variation that gives a nice clean screen
> afterwards in an MSDOS or Windows "DOS Prompt" environment:
>
> gawk 'BEGIN{$9999=OFS=" ";print}'
>
But note that this type of thing may fail on some awks that are
limited in the number of fields that are "assignable." It would
be good if all awks supported unlimited fields.
<snip>
Peter
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Patrice Neff
> But note that this type of thing may fail on some awks that are
> limited in the number of fields that are "assignable." It would
> be good if all awks supported unlimited fields.
Yep.
$ mawk 'BEGIN{$99999=OFS=" ";print}'
mawk: line 1: $99999 exceeds maximum field(32767)
what a pity.
patrice