From: jmichel@... (Jean Michel)
Date: 2001-01-04T03:40:01+09:00
Subject: [ruby-talk:8579] Re: [RAA-ANN] strbsrt-0.0.1, string sorting extension

In article <Pine.LNX.4.21.0101030630450.3644-100000@candle.superlink.net>,
David Alan Black  <dblack@candle.superlink.net> wrote:
>Hello --
>
>I've just placed on RAA version 0.0.1 of strbsrt, an extension
>which provides sort_bytes and sort_bytes! methods for strings.
>(This grows out of the anagram discussion.)
>
>Comments and feedback are welcome.

qsort is suboptimal for sorting strings. To sort string str in C
(I write C code here, I don't know ruby internals) do

unsigned char *sort(unsigned char *str)
{ int count[256],i,j,l;unsigned char *p,*res;
  for(i=0;i<256;i++)count[i]=0;
  l=strlen(str);
  for(i=0;i<l;i++)count[str[i]]++;
  p=res=malloc(l+1);
  for(i=0;i<256;i++)for(j=0;j<count[i];j++)*p++=i;
  *p=0;
  return res;
}

This should be faster than qsort as soon as the string is long enough
(I have not determined the cutoff point).

Best regards,
    Jean MICHEL