formatting the output of a function
Hi all
I created a function that returns a set of records. This function returns an integer and a float as the record fields. I have a problem in this function, it truncates the output. e.g. 1342 is displayed as 134, 456.46 is displayed as 456. In other words, it displays the first 3 digits only of a number, whether it is integer of float. I traced the function and the results are computed correctly. I use PostgreSQL 8.2.4. Following is a piece of my code.
int counter;
float result;
//some code
char **output;
output = (char**)palloc(2*sizeof(char*)); //allocate space for two string pointer
output[0] = (char*)palloc(sizeof(int)); //allocate space for a string that accepts an integer
output[1] = (char*)palloc(sizeof(double)); //allocate space for a string that accepts an integer
snprintf(output[0], sizeof(int), "%d", counter);
snprintf(output[1], sizeof(float), "%.5f", result);
HeapTuple data;
Datum finalResult;
data = BuildTupleFromCStrings(attinmeta, output);
finalResult = HeapTupleGetDatum(data);
SRF_RETURN_NEXT(funcctx, finalResult);
---------------
Any idea what could be the cause of this error?
Regards
Islam Hegazy
On Wed, Jun 06, 2007 at 01:45:43PM -0600, Islam Hegazy wrote:
output[0] = (char*)palloc(sizeof(int)); //allocate space for a string that accepts an integer
No it doesn't, it allocates space for an integer
output[1] = (char*)palloc(sizeof(double)); //allocate space for a string that accepts an integer
This allocates space for a double.
snprintf(output[0], sizeof(int), "%d", counter);
snprintf(output[1], sizeof(float), "%.5f", result);
And here you're using sizeof(float) which is even smaller.
Don't try to be smart with the sizes, just use 16 bytes for both and in
the snprintf use 16 also, then everything will work fine.
HeapTuple data;
Datum finalResult;
data = BuildTupleFromCStrings(attinmeta, output);
Although I think you're going the long way round, you can build a tuple
from the integer wtihout making a string first...
Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
Show quoted text
From each according to his ability. To each according to his ability to litigate.
Islam Hegazy wrote:
Hi all
I created a function that returns a set of records. This function returns an integer and a float as the record fields. I have a problem in this function, it truncates the output. e.g. 1342 is displayed as 134, 456.46 is displayed as 456. In other words, it displays the first 3 digits only of a number, whether it is integer of float. I traced the function and the results are computed correctly. I use PostgreSQL 8.2.4. Following is a piece of my code.
output[0] = (char*)palloc(sizeof(int)); //allocate space for a string that accepts an integer
output[1] = (char*)palloc(sizeof(double)); //allocate space for a string that accepts an integer
I don't really do C any more, but I don't think these do what you want.
I think here you're allocating space for an integer/double, not for the
string representation of them (i.e. 4/8 bytes). I'm surprised you're not
just getting a crash.
snprintf(output[0], sizeof(int), "%d", counter);
snprintf(output[1], sizeof(float), "%.5f", result);
--
Richard Huxton
Archonet Ltd