Gets the floating-point status word.
#include <float.h>
unsigned int _status87( void );
The _status87 function gets the floating-point status word. The status word is a combination of the 8087/80287/80387 status word and other conditions detected by the 8087/80287/80387 exception handler, such as floating-point stack overflow and underflow.
The bits in the value returned indicate the floating-point status. See the FLOAT.H include file for a complete definition of the bits returned by _status87.
Note that many of the math library functions modify the 8087/80287 status word, with unpredictable results. Return values from _clear87 and _status87 become more reliable as fewer floating-point operations are performed between known states of the floating-point status word.
Standards:None
16-Bit:DOS, QWIN, WIN, WIN DLL
32-Bit:DOS32X
/* STATUS87.C: This program creates various floating-point errors and
* then uses _status87 to display messages indicating these problems.
* Compile this program with optimizations disabled (/Od). Otherwise,
* the optimizer will remove the code related to the unused floating-
* point values.
*/
#include <stdio.h>
#include <float.h>
void main( void )
{
double a = 1e-40, b;
float x, y;
printf( "Status = %.4x - clear\n",_status87() );
/* Assignment into y is inexact & underflows: */
y = a;
printf( "Status = %.4x - inexact, underflow\n", _status87() );
/* y is denormal: */
b = y;
printf( "Status = %.4x - inexact underflow, denormal\n", _status87() );
/* Clear user 8087: */
_clear87();
}
Status = 0000 - clear
Status = 0030 - inexact, underflow
Status = 0032 - inexact underflow, denormal