 | | From: | Robert Wimmer | | Subject: | type text in c functions | | Date: | Sun, 19 Dec 2004 01:16:44 +0000 |
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 | i tried to write a simple typechecking function in c. but it does not work
correct
-- CODE --
#include
#include
#include
PG_FUNCTION_INFO_V1(text_to_card);
Datum text_to_card(PG_FUNCTION_ARGS)
{
int i,l;
int32 ret;
text *t = PG_GETARG_TEXT_P(0);
l = VARSIZE(t) - VARHDRSZ;
for (i = 0; i < l; i++) { if ( (t->vl_dat[i] < '0') || (t->vl_dat[i] >
'9')) break; }
if (i==l) ret = 0;
else ret = i;
PG_RETURN_INT32(ret);
}
--END --
this function should check if it is possible to cast a TEXT in an unsigned
INTEGER. if OK it returns 0
otherwise the position in the string where the error occured.
( so you can produce error messages like ERROR[234] text_to_card('paramete')
failed at <3>)
i assumed - after reading the corresponding header files and docs and google
- the type structure of a text as above.
i only get zeros and ones as result
the algorithm works fine in 'normal' c.
is there a possibilty to treat a TEXT parameter like a char array ?
thanks and regards sepp
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| | From: | Tom Lane | | Subject: | Re: type text in c functions | | Date: | Sat, 18 Dec 2004 22:21:07 -0500 |
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| "Robert Wimmer" writes:
> text *t = PG_GETARG_TEXT_P(0);
> l = VARSIZE(t) - VARHDRSZ;
> for (i = 0; i < l; i++) { if ( (t->vl_dat[i] < '0') || (t->vl_dat[i] >
> '9')) break; }
> if (i==l) ret = 0;
> else ret = i;
I think you need to rethink your return convention --- success and
failure at the first character both return 0.
Directly using the vl_dat field doesn't seem like good style (you won't
find it anywhere in the backend sources) but it works.
regards, tom lane
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