Originální popis anglicky:
lround, lroundf, lroundl - round to nearest integer value
Návod, kniha: POSIX Programmer's Manual
#include <math.h>
long lround(double
x);
long lroundf(float
x);
long lroundl(long double
x);
These functions shall round their argument to the nearest integer value,
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.
Upon successful completion, these functions shall return the rounded integer
value.
If
x is NaN, a domain error shall occur and an unspecified value is
returned.
If
x is +Inf, a domain error shall occur and an unspecified value is
returned.
If
x is -Inf, a domain error shall occur and an unspecified value is
returned.
If the correct value is positive and too large to represent as a
long, a
domain error shall occur and an unspecified value is returned.
If the correct value is negative and too large to represent as a
long, a
domain error shall occur and an unspecified value is returned.
These functions shall fail if:
- Domain Error
- The x argument is NaN or ±Inf, or the correct
value is not representable as an integer.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then
errno shall be set to [EDOM]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception shall be raised.
The following sections are informative.
None.
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.
These functions differ from the
lrint() functions in the default rounding
direction, with the
lround() functions rounding halfway cases away from
zero and needing not to raise the inexact floating-point exception for
non-integer arguments that round to within the range of the return type.
None.
feclearexcept() ,
fetestexcept() ,
llround() , the Base
Definitions volume of IEEE Std 1003.1-2001, Section 4.18,
Treatment of Error Conditions for Mathematical Functions,
<math.h>
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
.
