Przemek,
I cannot find such code in hbprintf.c.
In the line 1181: ++size;
Sorry, I needed added for testing the if( c != 0 ) and I thought that you would
see more clearly.
hb_printf_c() for sure sets trailing \0 byte in all cases even if buffer
is too small.
Yes, but return size accumulate the \0 byte (terminating null) and sprintf or
snprintf not.
It's also possible in 1183: while( c != 0 ); --size;
Welcome to the fantastic world of floating point arithmetic by Borland.
Yes I see. Thanks, now don't have differences in accuracy.
Best regards,
Xavi
Przemyslaw Czerpak escribió:
On Wed, 28 Jan 2009, Xavi wrote:
Hi Xavi,
The return value does not include the terminating null byte in the count.
...
if( c != 0 ) ++size;
}
while( c != 0 );
...
I cannot find such code in hbprintf.c.
hb_printf_c() for sure sets trailing \0 byte in all cases even if buffer
is too small.
I made a few tests with BCC and Spd add #define snprintf hb_snprintf_c
and the basics are working but with differences in accuracy.
? Sql_sprintf( "Phi = %.15f", (1 + 5**0.5) / 2 ) )
Phi = 1.618033988749895 snprintf() it's Ok
Phi = 1.618033981323242 hb_snprintf_c()
Welcome to the fantastic world of floating point arithmetic by Borland.
Try this code with this "incredible" compiler:
#include <stdio.h>
#include <math.h>
#include <float.h>
int main( void )
{
printf( "[%.15f]\n", ((1 + pow(5.0,0.5)) / 2 ) );
_fpclass( 0 );
printf( "[%.15f]\n", ((1 + pow(5.0,0.5)) / 2 ) );
return 0;
}
It's good to know that calling _fpclass() reduce floating point
precision to 'float' type even if you use 'double' or 'long double'.
It will create problems for us also in HVM calculations if 3-r party
code execute this function, f.e. try this:
proc main()
? str( (1 + 5**0.5) / 2, 20, 15 )
_fpclass()
? str( (1 + 5**0.5) / 2, 20, 15 )
return
#pragma begindump
#include <math.h>
#include <float.h>
HB_FUNC( _FPCLASS )
{
_fpclass( 0 );
}
#pragma enddump
I'll disable _fplcass() and checking for +-inf in BCC builds.
It will fix the results and I think we should document it somewhere
to avoid possible problems which can be created by 3-r party code
which will try to use it.
_fplcass() is forbidden in BCC builds !!!! ;-)
==============================================
best regards,
Przemek
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