Re: return varchar from C function

>"Pavel Stehule" <pavel.stehule@hotmail.com> writes:
>
> >
> > Datum *const_fce(PG_FUNCTION_ARGS)
> > {
> >    text *txt = palloc(5 + VARHDRSZ);
> >    memcpy(VARDATA(txt), "pavel", 5);
> >    VARATT_SIZE(txt) = 5 + VARHDRSZ;
> >
> >    PG_RETURN_TEXT_P(txt);
> > }
>
>Much better practice is to use the input function of the data type you want 
>to
>convert to:
>
>{
>    text *txt = DatumGetTextP(DirectFunctionCall1(textin, 
>CStringGetDatum("pavel")));
>    PG_RETURN_TEXT_P(txt);
>}
>

Generally we want to do something with text value (concat, trim, ..) and 
then call textin isn't practic. Respective, for bussness processes 
implemented in C is textin and similar functions right. For string toolkit 
is better direct work with VARLENA struct.

Regards and thank you note

Pavel

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