NAME

       round, roundf, roundl - round to the nearest integer value in a floating-point format

SYNOPSIS

       #include <math.h>

       double round(double x);
       float roundf(float x);
       long double roundl(long double x);

DESCRIPTION

       These  functions shall round their argument to the nearest integer value in floating-point
       format, rounding halfway  cases  away  from  zero,  regardless  of  the  current  rounding
       direction.

       An  application  wishing  to  check for error situations should set errno to zero and call
       feclearexcept(FE_ALL_EXCEPT) before calling these functions.  On return, if errno is  non-
       zero  or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero,
       an error has occurred.

RETURN VALUE

       Upon successful completion, these functions shall return the rounded integer value.

       If x is NaN, a NaN shall be returned.

       If x is ±0 or ±Inf, x shall be returned.

       If the correct value would  cause  overflow,  a  range  error  shall  occur  and  round(),
       roundf(),  and  roundl()  shall  return  the value of the macro ±HUGE_VAL, ±HUGE_VALF, and
       ±HUGE_VALL (with the same sign as x), respectively.

ERRORS

       These functions may fail if:

       Range Error
              The result overflows.

       If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be
       set  to  [ERANGE].  If  the integer expression (math_errhandling & MATH_ERREXCEPT) is non-
       zero, then the overflow floating-point exception shall be raised.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       On  error,  the  expressions  (math_errhandling  &  MATH_ERRNO)  and  (math_errhandling  &
       MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       feclearexcept()  ,  fetestexcept()  , the Base Definitions volume of IEEE Std 1003.1-2001,
       Section 4.18, Treatment of Error Conditions for Mathematical Functions, <math.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .