_fpreset

Reinitializes floating-point math package.

Defined in header <float.h>

Syntax

#include <float.h>
void _fpreset(void);

Portability

Remarks

_fpreset reinitializes the floating-point math package. This function is usually used in conjunction with system or the exec... or spawn... functions.

b^

Under DOS, if an 80x87 coprocessor is used in a program, a child process (executed by system or by an exec... or spawn... function) might alter the parent process's floating-point state.

If you use an 80x87, take the following precautions:

EI Do not call system or an exec... or spawn... function while a floating-point expression is being evaluated. D Call _fpreset to reset the floating-point state after using system, exec..., or spawn... if there is any chance that the child process performed a floating-point operation with the 80x87.

Return value

None.

See also

• _clear87
• _control87
• exec
• spawn_status87
• system

Example

include  <stdio.h>
#include <float.h>
#include <setjinp.h>
#include <signal.h>
#include <process.h>
#include <conio.h>

#ifdef   cplusplus
    typedef void  (*fptr)(int);
telse
    typedef void  (*fptr)();
tendif

]inp_buf reenter;

/* define a handler  for trapping floating
   point errors */
void float_trap(int  sig)
{
   printf( "Trapping floating point error,");
   printf ("signal is %d\n",sig);
   printf ("Press a key to continue\n");
   getchO ;
   /* Reset the 8087  chip or emulator to clear any extraneous garbage.  */
   _fpreset ();
   /* return to the problem  spot */
   longjmp (reenter, -1);
}
int main (void)
float one = 3.14,  two = 0.0;
/* Install signal handler  for floating point exception. */
signal (SIGFPE, (fptr)float_trap);
printf ("Generating a math error,");
printf ("press a key\n");
getchO ;
if  (setjmp(reenter) == 0)
   one /= two;
printf ("Returned from signal trap\n");
return 0;

Differences from modern implementations

Nothing recorded yet.

Modern references

• Microsoft C runtime (search)

These are search links, not yet checked by hand.

Extraction notes

• heading `Jpreset` read as `_fpreset`

Stable link: /3.1/float.h/_fpreset/ · short form /3.1/_fpreset/