c99 [ flag... ] file... -lm [ library... ] #include <math.h>
long lround(double x);
long lroundf(float x);
These functions round their argument to the nearest integer value, rounding halfway cases away from zero, regardless of the current rounding direction.
Upon successful completion, these functions return the rounded integer value.
If x is NaN, a domain error occurs and an unspecified value is returned.
If x is +Inf, a domain error occurs and an unspecified value is returned.
If x is -Inf, a domain error occurs and an unspecified value is returned.
If the correct value is positive and too large to represent as a long, a domain error occurs and an unspecified value is returned.
If the correct value is negative and too large to represent as a long, a domain error occurs and an unspecified value is returned.
These functions will 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_ERREXCEPT) is non-zero, then the invalid floating-point exception is raised.
An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE | ATTRIBUTE VALUE |
Interface Stability | Standard |
MT-Level | MT-Safe |
feclearexcept(3M), fetestexcept(3M), llround(3M), math.h(3HEAD), attributes(5), standards(5)