Re: [HACKERS] substring extraction

On Fri, 26 Nov 1999, jose soares wrote:

> Try this:
> 
> --returns the $2 field delimited by $3
> drop function field(text,int,text);
> create function field(text,int,text) returns text as
> 'declare
>         string text;
>         pos int2:= 0;
>         pos1 int2:= 0;
>         times int2:= 0;
>         totpos int2:= 0;
> begin
>         times:= $2 - 1;
>         string:= $1;
>         while totpos < times loop
>                 string:= substr(string,pos+1);
>                 pos:= strpos(string,$3);
>                 totpos:= totpos + 1;
>         end loop;
>         string:= substr(string,pos+1);
>         pos1:= strpos(string,$3);
>         return substr(string,1,pos1 - 1);
>  end;
> ' language 'plpgsql';
> 
Oh, it is great! But my implementation in C for this is 
a little longer (only) :-) 

I send this question to the hacker list because "extract delimited 
substring" is not a abnormal uses's request, and (IMHO) will very 
good if this will in PgSQL. How much uses known write this in 
C or any PL? 

'C' implementafion "extract delimited substring":
-----------------------------------------------
text
*strcut( text *string, char *d, int field )
{char    *ptr     = NULL,     *p     = NULL,    *pe     = NULL;text    *result = NULL;int    siz;ptr  =
VARDATA(string);*(ptr+(VARSIZE(string) - VARHDRSZ)) = '\0';for(p = ptr; *p != '\0'; p++) {    if (field == 1)
break;   if (*p == (int) d)        --field;}    if (!*p)    return textin("");    for(pe = p; *pe != '\0'; pe++) {
if(*pe == (int) d)        break;}    result = (text *) palloc(sizeof(text) * (siz = pe - p) +
VARHDRSZ);strncpy(VARDATA(result),p, siz);*(VARDATA(result) + siz) = '\0';     VARSIZE(result) = siz + VARHDRSZ;return
result;
}

CREATE FUNCTION         strcut(text, char, int)       RETURNS         text       AS              '@module_dir@'
LANGUAGE       'c'; 
 

template1=> select strcut('aaa.bbb.ccc', '.', 2);
strcut
------
bbb

                    Karel