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From: Ed Morton <mortonspam@gmail.com>
Newsgroups: comp.lang.awk
Subject: Re: FIELDWIDTHS helper
Date: Sun, 10 Aug 2025 14:25:33 -0500
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Xref: csiph.com comp.lang.awk:10005

On 8/6/2025 4:23 AM, Bruce wrote:
> The other day I found myself unable to count field sizes accurately so I
> wrote this little helper.
> 
> NR == 1 { # Pick a line
>      print
>      nf = split(FIELDWIDTHS, fw)
>      for (i = 1; i <= nf; i++)
>          for (j = 1; j <= fw[i]; j++)
>              printf "%d", (i % 10)
>      print ""
> }

FWIW you could do that without nested loops and without using 
FIELDWIDTHS so it'll work in any POSIX awk, not just gawk:

NR == 1 { # Pick a line
     for (i = 1; i <= NF; i++) {
         out = sprintf("%*s", length($i), "")
         gsub(/ /, i%10, out)
         printf "%s", out
     }
     print ""
}

Regards,

     Ed.