function
<cfenv>
fegetround
Get rounding direction mode
Returns a value that indicates the rounding direction mode, as specified in the current floating point environment.
Whether the value returned by this function is the same as FLT_ROUNDS in <cfloat> is unspecified.
Return Value
If the current rounding mode was successfully determined by the function and is supported by the implementation, the function returns a value for which a corresponding macro is defined:
Certain library implementations may support additional floating-point rounding directions values (with their corresponding macros also beginning with FE_).
Libraries may define in
<fenv.h> only the macro values above they support (the others may not be defined).
At least all of the above macro values are defined in
<cfenv>.
Example
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/* fegetround / rint example */
#include <stdio.h> /* printf */
#include <fenv.h> /* fegetround, FE_* */
#include <math.h> /* rint */
int main ()
{
printf ("rounding using ");
switch (fegetround()) {
case FE_DOWNWARD: printf ("downward"); break;
case FE_TONEAREST: printf ("to-nearest"); break;
case FE_TOWARDZERO: printf ("toward-zero"); break;
case FE_UPWARD: printf ("upward"); break;
default: printf ("unknown");
}
printf (" rounding:\n");
printf ( "rint (2.3) = %.1f\n", rint(2.3) );
printf ( "rint (3.8) = %.1f\n", rint(3.8) );
printf ( "rint (-2.3) = %.1f\n", rint(-2.3) );
printf ( "rint (-3.8) = %.1f\n", rint(-3.8) );
return 0;
}
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Possible output:
Rounding using to-nearest rounding:
rint (2.3) = 2.0
rint (3.8) = 4.0
rint (-2.3) = -2.0
rint (-3.8) = -4.0
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Data races
Each thread maintains a separate floating-point environment with its own state. Spawning a new thread copies the current state. [This applies to C11 and C++11 implementations]
Exceptions
No-throw guarantee: this function never throws exceptions.
See also
- fesetround
- Set rounding direction mode (function)
- fegetenv
- Get floating-point environment (function)
- rint
- Round to integral value (function)