Re: version 1 C-Language Functions

"Gowey, Geoffrey" <ggowey(at)rxhope(dot)com> writes:
> No example that I have run across illustrates how to convert
> a param entered to be used w/ regular c functions (in this case
> strcat).

I think the technique exhibited in the 7.1 contrib/soundex module is
about the cleanest: use the text type's I/O conversion functions.
Preferably with macros to hide the notational cruft:

#define _textin(str) DatumGetPointer(DirectFunctionCall1(textin, CStringGetDatum(str)))
#define _textout(str) DatumGetPointer(DirectFunctionCall1(textout, PointerGetDatum(str)))

/*
* SQL function: text_soundex(text) returns text
*/
PG_FUNCTION_INFO_V1(text_soundex);

Datum
text_soundex(PG_FUNCTION_ARGS)
{
char outstr[SOUNDEX_LEN + 1];
char *arg;

arg = _textout(PG_GETARG_TEXT_P(0));

soundex(arg, outstr);

PG_RETURN_TEXT_P(_textin(outstr));
}

'arg' and 'outstr' are null-terminated strings here.

regards, tom lane